Rework GLContextSwitch, get rid of RendererContextManager (#18601)

ci/licenses_golden/licenses_flutter

@@ -575,6 +575,11 @@ FILE: ../../../flutter/shell/common/engine.cc
 FILE: ../../../flutter/shell/common/engine.h
 FILE: ../../../flutter/shell/common/fixtures/shell_test.dart
 FILE: ../../../flutter/shell/common/fixtures/shelltest_screenshot.png
+FILE: ../../../flutter/shell/common/gl_context_switch.cc
+FILE: ../../../flutter/shell/common/gl_context_switch.h
+FILE: ../../../flutter/shell/common/gl_context_switch_test.cc
+FILE: ../../../flutter/shell/common/gl_context_switch_test.h
+FILE: ../../../flutter/shell/common/gl_context_switch_unittests.cc
 FILE: ../../../flutter/shell/common/input_events_unittests.cc
 FILE: ../../../flutter/shell/common/isolate_configuration.cc
 FILE: ../../../flutter/shell/common/isolate_configuration.h
@@ -590,11 +595,6 @@ FILE: ../../../flutter/shell/common/pointer_data_dispatcher.cc
 FILE: ../../../flutter/shell/common/pointer_data_dispatcher.h
 FILE: ../../../flutter/shell/common/rasterizer.cc
 FILE: ../../../flutter/shell/common/rasterizer.h
-FILE: ../../../flutter/shell/common/renderer_context_manager.cc
-FILE: ../../../flutter/shell/common/renderer_context_manager.h
-FILE: ../../../flutter/shell/common/renderer_context_manager_unittests.cc
-FILE: ../../../flutter/shell/common/renderer_context_test.cc
-FILE: ../../../flutter/shell/common/renderer_context_test.h
 FILE: ../../../flutter/shell/common/run_configuration.cc
 FILE: ../../../flutter/shell/common/run_configuration.h
 FILE: ../../../flutter/shell/common/shell.cc
@@ -942,6 +942,8 @@ FILE: ../../../flutter/shell/platform/darwin/ios/ios_surface_metal.h
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_surface_metal.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_surface_software.h
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_surface_software.mm
+FILE: ../../../flutter/shell/platform/darwin/ios/ios_switchable_gl_context.h
+FILE: ../../../flutter/shell/platform/darwin/ios/ios_switchable_gl_context.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/platform_view_ios.h
 FILE: ../../../flutter/shell/platform/darwin/ios/platform_view_ios.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/rendering_api_selection.h

flow/BUILD.gn

@@ -73,7 +73,7 @@ source_set("flow") {
   deps = [
     "//flutter/common",
     "//flutter/fml",
-    "//flutter/shell/common:surface_frame",
+    "//flutter/shell/common:common_standalone",
     "//third_party/skia",
   ]
 

shell/common/BUILD.gn

@@ -97,8 +97,6 @@ source_set("common") {
     "pointer_data_dispatcher.h",
     "rasterizer.cc",
     "rasterizer.h",
-    "renderer_context_manager.cc",
-    "renderer_context_manager.h",
     "run_configuration.cc",
     "run_configuration.h",
     "shell.cc",
@@ -120,7 +118,7 @@ source_set("common") {
   ]
 
   deps = [
-    ":surface_frame",
+    ":common_standalone",
     "//flutter/assets",
     "//flutter/common",
     "//flutter/flow",
@@ -142,8 +140,10 @@ source_set("common") {
   public_configs = [ "//flutter:config" ]
 }
 
-source_set("surface_frame") {
+source_set("common_standalone") {
   sources = [
+    "gl_context_switch.cc",
+    "gl_context_switch.h",
     "surface_frame.cc",
     "surface_frame.h",
   ]
@@ -203,8 +203,9 @@ if (enable_unittests) {
     testonly = true
 
     sources = [
-      "renderer_context_test.cc",
-      "renderer_context_test.h",
+      "gl_context_switch_test.cc",
+      "gl_context_switch_test.h",
+      "gl_context_switch_unittests.cc",
       "shell_test.cc",
       "shell_test.h",
       "shell_test_external_view_embedder.cc",
@@ -216,6 +217,7 @@ if (enable_unittests) {
     ]
 
     public_deps = [
+      ":common_standalone",
       "//flutter/flow",
       "//flutter/fml/dart",
       "//flutter/lib/ui",
@@ -267,7 +269,6 @@ if (enable_unittests) {
       "input_events_unittests.cc",
       "persistent_cache_unittests.cc",
       "pipeline_unittests.cc",
-      "renderer_context_manager_unittests.cc",
       "shell_unittests.cc",
     ]
 

shell/common/gl_context_switch.cc

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "gl_context_switch.h"
+
+namespace flutter {
+
+SwitchableGLContext::SwitchableGLContext() = default;
+
+SwitchableGLContext::~SwitchableGLContext() = default;
+
+GLContextResult::GLContextResult() = default;
+GLContextResult::~GLContextResult() = default;
+GLContextResult::GLContextResult(bool static_result) : result_(static_result){};
+bool GLContextResult::GetResult() {
+  return result_;
+};
+
+GLContextDefaultResult::~GLContextDefaultResult() = default;
+GLContextDefaultResult::GLContextDefaultResult(bool static_result)
+    : GLContextResult(static_result){};
+
+GLContextSwitch::GLContextSwitch(std::unique_ptr<SwitchableGLContext> context)
+    : context_(std::move(context)) {
+  FML_CHECK(context_ != nullptr);
+  result_ = context_->SetCurrent();
+};
+
+GLContextSwitch::~GLContextSwitch() {
+  context_->RemoveCurrent();
+};
+
+}  // namespace flutter

shell/common/gl_context_switch.h

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_COMMON_GL_CONTEXT_SWITCH_H_
+#define FLUTTER_SHELL_COMMON_GL_CONTEXT_SWITCH_H_
+
+#include <functional>
+#include <memory>
+#include <vector>
+
+#include "flutter/fml/logging.h"
+#include "flutter/fml/macros.h"
+
+namespace flutter {
+
+//------------------------------------------------------------------------------
+/// An abstract class represents a gl context that can be switched by
+/// GLContextSwitch
+///
+/// The subclass should wrap a "Context" object inside this class. For example,
+/// in iOS while using GL rendering surface, the subclass should wrap an
+/// |EAGLContext|.
+class SwitchableGLContext {
+ public:
+  //------------------------------------------------------------------------------
+  /// Implement this to set the context wrapped by this |SwitchableGLContext|
+  /// object to the current context.
+  virtual bool SetCurrent() = 0;
+
+  //------------------------------------------------------------------------------
+  /// Implement this to remove the context wrapped by this |SwitchableGLContext|
+  /// object from current context;
+  virtual bool RemoveCurrent() = 0;
+
+  SwitchableGLContext();
+
+  virtual ~SwitchableGLContext();
+
+  FML_DISALLOW_COPY_AND_ASSIGN(SwitchableGLContext);
+};
+
+//------------------------------------------------------------------------------
+/// Represents the result of setting a gl context.
+/// This class exists because context results are used in places applies to all
+/// the platforms. On certain platforms(for example lower end iOS devices that
+/// uses gl), a |GLContextSwitch| is required to protect flutter's gl contect
+/// from being polluted by other programs(embedded platform views). A
+/// |GLContextSwitch| is a subclass of |GLContextResult|, which can be returned
+/// on platforms that requires context switching. A |GLContextDefaultResult| is
+/// also a subclass of |GLContextResult|, which can be returned on platforms
+/// that doesn't require context switching.
+class GLContextResult {
+ public:
+  GLContextResult();
+  virtual ~GLContextResult();
+
+  //----------------------------------------------------------------------------
+  // Returns true if the gl context is set successfully.
+  bool GetResult();
+
+ protected:
+  GLContextResult(bool static_result);
+  bool result_;
+
+  FML_DISALLOW_COPY_AND_ASSIGN(GLContextResult);
+};
+
+//------------------------------------------------------------------------------
+/// The default implementation of |GLContextResult|.
+///
+/// Use this class on platforms that doesn't require gl context switching.
+/// * See also |GLContextSwitch| if the platform requires gl context switching.
+class GLContextDefaultResult : public GLContextResult {
+ public:
+  //----------------------------------------------------------------------------
+  /// Constructs a |GLContextDefaultResult| with a static result.
+  ///
+  /// Used this on platforms that doesn't require gl context switching. (For
+  /// example, metal on iOS)
+  ///
+  /// @param  static_result a static value that will be returned from
+  /// |GetResult|
+  GLContextDefaultResult(bool static_result);
+
+  ~GLContextDefaultResult() override;
+
+  FML_DISALLOW_COPY_AND_ASSIGN(GLContextDefaultResult);
+};
+
+//------------------------------------------------------------------------------
+/// Switches the gl context to the a context that is passed in the
+/// constructor.
+///
+/// In destruction, it should restore the current context to what was
+/// before the construction of this switch.
+class GLContextSwitch final : public GLContextResult {
+ public:
+  //----------------------------------------------------------------------------
+  /// Constructs a |GLContextSwitch|.
+  ///
+  /// @param  context The context that is going to be set as the current
+  /// context. The |GLContextSwitch| should not outlive the owner of the gl
+  /// context wrapped inside the `context`.
+  GLContextSwitch(std::unique_ptr<SwitchableGLContext> context);
+
+  ~GLContextSwitch() override;
+
+ private:
+  std::unique_ptr<SwitchableGLContext> context_;
+
+  FML_DISALLOW_COPY_AND_ASSIGN(GLContextSwitch);
+};
+
+}  // namespace flutter
+
+#endif

shell/common/renderer_context_test.cc → shell/common/gl_context_switch_test.cc

@@ -2,37 +2,41 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "renderer_context_test.h"
+#include "gl_context_switch_test.h"
+
+#include "flutter/fml/thread_local.h"
 
 namespace flutter {
 namespace testing {
 
 FML_THREAD_LOCAL fml::ThreadLocalUniquePtr<int> current_context;
 
-RendererContextTest::RendererContextTest() = default;
+GLContextSwitchTest::GLContextSwitchTest() = default;
 
-TestRendererContext::TestRendererContext(int context) : context_(context){};
+TestSwitchableGLContext::TestSwitchableGLContext(int context)
+    : context_(context){};
 
-TestRendererContext::~TestRendererContext() = default;
+TestSwitchableGLContext::~TestSwitchableGLContext() = default;
 
-bool TestRendererContext::SetCurrent() {
+bool TestSwitchableGLContext::SetCurrent() {
   SetCurrentContext(context_);
   return true;
 };
 
-void TestRendererContext::RemoveCurrent() {
+bool TestSwitchableGLContext::RemoveCurrent() {
   SetCurrentContext(-1);
+  return true;
 };
 
-int TestRendererContext::GetContext() {
+int TestSwitchableGLContext::GetContext() {
   return context_;
 };
 
-int TestRendererContext::GetCurrentContext() {
+int TestSwitchableGLContext::GetCurrentContext() {
   return *(current_context.get());
 };
 
-void TestRendererContext::SetCurrentContext(int context) {
+void TestSwitchableGLContext::SetCurrentContext(int context) {
   current_context.reset(new int(context));
 };
 }  // namespace testing

shell/common/renderer_context_test.h → shell/common/gl_context_switch_test.h

@@ -5,37 +5,35 @@
 #ifndef FLUTTER_SHELL_RENDERER_CONTEXT_TEST_H_
 #define FLUTTER_SHELL_RENDERER_CONTEXT_TEST_H_
 
-#include "flutter/fml/thread_local.h"
+#include "gl_context_switch.h"
 #include "gtest/gtest.h"
-#include "renderer_context_manager.h"
 
 namespace flutter {
 namespace testing {
 
-class RendererContextTest : public ::testing::Test {
+class GLContextSwitchTest : public ::testing::Test {
  public:
-  RendererContextTest();
+  GLContextSwitchTest();
 };
 
 //------------------------------------------------------------------------------
 /// The renderer context used for testing
-class TestRendererContext : public RendererContext {
+class TestSwitchableGLContext : public SwitchableGLContext {
  public:
-  TestRendererContext(int context);
+  TestSwitchableGLContext(int context);
 
-  ~TestRendererContext() override;
+  ~TestSwitchableGLContext() override;
 
   bool SetCurrent() override;
 
-  void RemoveCurrent() override;
+  bool RemoveCurrent() override;
 
   int GetContext();
 
   static int GetCurrentContext();
 
   //------------------------------------------------------------------------------
-  /// Set the current context without going through the
-  /// |RendererContextManager|.
+  /// Set the current context
   ///
   /// This is to mimic how other programs outside flutter sets the context.
   static void SetCurrentContext(int context);
@@ -43,7 +41,7 @@ class TestRendererContext : public RendererContext {
  private:
   int context_;
 
-  FML_DISALLOW_COPY_AND_ASSIGN(TestRendererContext);
+  FML_DISALLOW_COPY_AND_ASSIGN(TestSwitchableGLContext);
 };
 }  // namespace testing
 }  // namespace flutter

shell/common/gl_context_switch_unittests.cc

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#define FML_USED_ON_EMBEDDER
+
+#include <functional>
+#include <future>
+#include <memory>
+
+#include "flutter/shell/common/gl_context_switch.h"
+#include "gl_context_switch_test.h"
+#include "gtest/gtest.h"
+
+namespace flutter {
+namespace testing {
+
+TEST_F(GLContextSwitchTest, SwitchKeepsContextCurrentWhileInScope) {
+  {
+    auto test_gl_context = std::make_unique<TestSwitchableGLContext>(0);
+    auto context_switch = GLContextSwitch(std::move(test_gl_context));
+    ASSERT_EQ(TestSwitchableGLContext::GetCurrentContext(), 0);
+  }
+  ASSERT_EQ(TestSwitchableGLContext::GetCurrentContext(), -1);
+}
+
+}  // namespace testing
+}  // namespace flutter

shell/common/rasterizer.cc

@@ -228,7 +228,8 @@ sk_sp<SkImage> Rasterizer::DoMakeRasterSnapshot(
               result = DrawSnapshot(surface, draw_callback);
             })
             .SetIfFalse([&] {
-              if (!surface_->MakeRenderContextCurrent()) {
+              auto context_switch = surface_->MakeRenderContextCurrent();
+              if (!context_switch->GetResult()) {
                 return;
               }
 

shell/common/renderer_context_manager.cc

-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "renderer_context_manager.h"
-
-namespace flutter {
-
-RendererContext::RendererContext() = default;
-
-RendererContext::~RendererContext() = default;
-
-RendererContextManager::RendererContextManager(
-    std::unique_ptr<RendererContext> context,
-    std::unique_ptr<RendererContext> resource_context)
-    : context_(std::move(context)),
-      resource_context_(std::move(resource_context)){};
-
-RendererContextManager::~RendererContextManager() = default;
-
-RendererContextManager::RendererContextSwitch
-RendererContextManager::MakeCurrent(std::unique_ptr<RendererContext> context) {
-  return RendererContextManager::RendererContextSwitch(*this,
-                                                       std::move(context));
-};
-
-RendererContextManager::RendererContextSwitch
-RendererContextManager::FlutterMakeCurrent() {
-  return MakeCurrent(std::move(context_));
-};
-
-RendererContextManager::RendererContextSwitch
-RendererContextManager::FlutterResourceMakeCurrent() {
-  return MakeCurrent(std::move(resource_context_));
-};
-
-bool RendererContextManager::PushContext(
-    std::unique_ptr<RendererContext> context) {
-  if (current_ == nullptr) {
-    current_ = std::move(context);
-    return current_->SetCurrent();
-  }
-  stored_.push_back(std::move(current_));
-  bool result = context->SetCurrent();
-  current_ = std::move(context);
-  return result;
-};
-
-void RendererContextManager::PopContext() {
-  if (stored_.empty()) {
-    current_->RemoveCurrent();
-    return;
-  }
-  current_ = std::move(stored_.back());
-  current_->SetCurrent();
-  stored_.pop_back();
-};
-
-RendererContextManager::RendererContextSwitch::RendererContextSwitch(
-    RendererContextManager& manager,
-    std::unique_ptr<RendererContext> context)
-    : manager_(manager) {
-  bool result = manager_.PushContext(std::move(context));
-  result_ = result;
-};
-
-RendererContextManager::RendererContextSwitch::~RendererContextSwitch() {
-  manager_.PopContext();
-};
-
-bool RendererContextManager::RendererContextSwitch::GetResult() {
-  return result_;
-};
-}  // namespace flutter

shell/common/renderer_context_manager.h

-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef FLUTTER_SHELL_COMMON_RENDERER_CONTEXT_MANAGER_H_
-#define FLUTTER_SHELL_COMMON_RENDERER_CONTEXT_MANAGER_H_
-
-#include <functional>
-#include <memory>
-#include <vector>
-
-#include "flutter/fml/logging.h"
-#include "flutter/fml/macros.h"
-
-namespace flutter {
-
-//------------------------------------------------------------------------------
-/// An abstract class represents a renderer context
-///
-/// The subclass should wrap a "Context" object inside this class. For example,
-/// in iOS while using GL rendering surface, the subclass should wrap an
-/// |EAGLContext|.
-class RendererContext {
- public:
-  //------------------------------------------------------------------------------
-  /// Implement this to set the context wrapped by this |RendererContext| object
-  /// to the current context.
-  virtual bool SetCurrent() = 0;
-
-  //------------------------------------------------------------------------------
-  /// Implement this to remove the context wrapped by this |RendererContext|
-  /// object from current context;
-  virtual void RemoveCurrent() = 0;
-
-  RendererContext();
-
-  virtual ~RendererContext();
-
-  FML_DISALLOW_COPY_AND_ASSIGN(RendererContext);
-};
-
-//------------------------------------------------------------------------------
-/// Manages the renderer context.
-///
-/// Initially, the |RendererContextManager| doesn't know any context that is set
-/// by other programs (e.g. a plugin). To make sure not to pollute the other
-/// context, use `MakeCurrent` to set other context, so |RendererContextManager|
-/// has a reference of the other context. Ideally, this process has to be done
-/// everytime before a context used by Flutter is set, if the current context at
-/// the moment is not null or used by Flutter.
-class RendererContextManager {
- public:
-  //------------------------------------------------------------------------------
-  /// Switches the renderer context to the a context that is passed in the
-  /// constructor.
-  ///
-  /// In destruction, it should reset the current context back to what was
-  /// before the construction of this switch.
-  ///
-  class RendererContextSwitch {
-   public:
-    //----------------------------------------------------------------------------
-    /// Constructs a |RendererContextSwitch|.
-    ///
-    /// @param  manager A reference to the manager.
-    /// @param  context The context that is going to be set as the current
-    /// context.
-    RendererContextSwitch(RendererContextManager& manager,
-                          std::unique_ptr<RendererContext> context);
-
-    ~RendererContextSwitch();
-
-    //----------------------------------------------------------------------------
-    // Returns true if the context switching was successful.
-    bool GetResult();
-
-   private:
-    RendererContextManager& manager_;
-    bool result_;
-
-    FML_DISALLOW_COPY_AND_ASSIGN(RendererContextSwitch);
-  };
-
-  RendererContextManager(std::unique_ptr<RendererContext> context,
-                         std::unique_ptr<RendererContext> resource_context);
-
-  ~RendererContextManager();
-
-  //----------------------------------------------------------------------------
-  /// @brief      Make the `context` to be the current context. It can be used
-  /// to set a context set by other programs to be the current context in
-  /// |RendererContextManager|. Which make sure Flutter doesn't pollute other
-  /// contexts.
-  ///
-  /// @return     A `RendererContextSwitch` which ensures the `context` is the
-  /// current context.
-  RendererContextSwitch MakeCurrent(std::unique_ptr<RendererContext> context);
-
-  //----------------------------------------------------------------------------
-  /// @brief      Make the context Flutter uses on the raster thread for
-  /// onscreen rendering to be the current context.
-  ///
-  /// @return     A `RendererContextSwitch` which ensures the current context is
-  /// the `context` that used in the constructor.
-  RendererContextSwitch FlutterMakeCurrent();
-
-  //----------------------------------------------------------------------------
-  /// @brief      Make the context Flutter uses for performing texture upload on
-  /// the IO thread to be the current context.
-  ///
-  /// @return     A `RendererContextSwitch` which ensures the current context is
-  /// the `resource_context` that used in the constructor.
-  RendererContextSwitch FlutterResourceMakeCurrent();
-
- private:
-  std::unique_ptr<RendererContext> context_;
-  std::unique_ptr<RendererContext> resource_context_;
-
-  std::unique_ptr<RendererContext> current_;
-
-  std::vector<std::unique_ptr<RendererContext>> stored_;
-
-  bool PushContext(std::unique_ptr<RendererContext> context);
-  void PopContext();
-
-  FML_DISALLOW_COPY_AND_ASSIGN(RendererContextManager);
-};
-
-}  // namespace flutter
-
-#endif

shell/common/renderer_context_manager_unittests.cc

-// Copyright 2013 The Flutter Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-#define FML_USED_ON_EMBEDDER
-
-#include <functional>
-#include <future>
-#include <memory>
-
-#include "flutter/shell/common/renderer_context_manager.h"
-#include "gtest/gtest.h"
-#include "renderer_context_test.h"
-
-namespace flutter {
-namespace testing {
-
-TEST_F(RendererContextTest, StartWithNoContextFlutterMakeCurrent) {
-  auto flutter_context = std::make_unique<TestRendererContext>(0);
-  auto flutter_resource_context = std::make_unique<TestRendererContext>(1);
-
-  RendererContextManager manager(std::move(flutter_context),
-                                 std::move(flutter_resource_context));
-  // started with current_context as -1
-  TestRendererContext::SetCurrentContext(-1);
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), -1);
-  {
-    // made flutter context to be the current
-    auto context_switch = manager.FlutterMakeCurrent();
-    ASSERT_EQ(TestRendererContext::GetCurrentContext(), 0);
-  }
-  // flutter context is popped
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), -1);
-}
-
-TEST_F(RendererContextTest, StartWithNoContextFlutterResourceMakeCurrent) {
-  auto flutter_context = std::make_unique<TestRendererContext>(0);
-  auto flutter_resource_context = std::make_unique<TestRendererContext>(1);
-
-  RendererContextManager manager(std::move(flutter_context),
-                                 std::move(flutter_resource_context));
-  // started with current_context as -1
-  TestRendererContext::SetCurrentContext(-1);
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), -1);
-  {
-    // made resource context to be the current
-    auto context_switch = manager.FlutterResourceMakeCurrent();
-    ASSERT_EQ(TestRendererContext::GetCurrentContext(), 1);
-  }
-  // flutter context is popped
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), -1);
-}
-
-TEST_F(RendererContextTest, StartWithSomeContextFlutterMakeCurrent) {
-  auto flutter_context = std::make_unique<TestRendererContext>(0);
-  auto flutter_resource_context = std::make_unique<TestRendererContext>(1);
-  auto some_context = std::make_unique<TestRendererContext>(2);
-
-  RendererContextManager manager(std::move(flutter_context),
-                                 std::move(flutter_resource_context));
-  // started with some_context
-  auto context_switch = manager.MakeCurrent(std::move(some_context));
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), 2);
-  {
-    // made flutter context to be the current
-    auto context_switch2 = manager.FlutterMakeCurrent();
-    ASSERT_EQ(TestRendererContext::GetCurrentContext(), 0);
-  }
-  // flutter context is popped
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), 2);
-}
-
-TEST_F(RendererContextTest, StartWithSomeContextFlutterResourceMakeCurrent) {
-  auto flutter_context = std::make_unique<TestRendererContext>(0);
-  auto flutter_resource_context = std::make_unique<TestRendererContext>(1);
-  auto some_context = std::make_unique<TestRendererContext>(2);
-
-  RendererContextManager manager(std::move(flutter_context),
-                                 std::move(flutter_resource_context));
-  // started with some_context
-  auto context_switch = manager.MakeCurrent(std::move(some_context));
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), 2);
-  {
-    // made resource context to be the current
-    auto context_switch2 = manager.FlutterResourceMakeCurrent();
-    ASSERT_EQ(TestRendererContext::GetCurrentContext(), 1);
-  }
-  // flutter context is popped
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), 2);
-}
-
-TEST_F(RendererContextTest, Nested) {
-  auto flutter_context = std::make_unique<TestRendererContext>(0);
-  auto flutter_resource_context = std::make_unique<TestRendererContext>(1);
-  auto some_context = std::make_unique<TestRendererContext>(2);
-
-  RendererContextManager manager(std::move(flutter_context),
-                                 std::move(flutter_resource_context));
-
-  // started with some_context
-  auto context_switch = manager.MakeCurrent(std::move(some_context));
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), 2);
-  {
-    // made flutter context to be the current
-    auto context_switch2 = manager.FlutterMakeCurrent();
-    ASSERT_EQ(TestRendererContext::GetCurrentContext(), 0);
-    {
-      // made resource context to be the current
-      auto context_switch2 = manager.FlutterResourceMakeCurrent();
-      ASSERT_EQ(TestRendererContext::GetCurrentContext(), 1);
-    }
-    // resource context is popped
-    ASSERT_EQ(TestRendererContext::GetCurrentContext(), 0);
-  }
-  // flutter context is popped
-  ASSERT_EQ(TestRendererContext::GetCurrentContext(), 2);
-}
-
-}  // namespace testing
-}  // namespace flutter

shell/common/shell_test_platform_view_gl.cc

@@ -44,8 +44,9 @@ PointerDataDispatcherMaker ShellTestPlatformViewGL::GetDispatcherMaker() {
 }
 
 // |GPUSurfaceGLDelegate|
-bool ShellTestPlatformViewGL::GLContextMakeCurrent() {
-  return gl_surface_.MakeCurrent();
+std::unique_ptr<GLContextResult>
+ShellTestPlatformViewGL::GLContextMakeCurrent() {
+  return std::make_unique<GLContextDefaultResult>(gl_surface_.MakeCurrent());
 }
 
 // |GPUSurfaceGLDelegate|

shell/common/shell_test_platform_view_gl.h

@@ -47,7 +47,7 @@ class ShellTestPlatformViewGL : public ShellTestPlatformView,
   PointerDataDispatcherMaker GetDispatcherMaker() override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<GLContextResult> GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;

shell/common/shell_test_platform_view_vulkan.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/common/shell_test_platform_view_vulkan.h"
+#include "flutter/shell/common/gl_context_switch.h"
 #include "flutter/vulkan/vulkan_utilities.h"
 
 namespace flutter {

shell/common/surface.cc

@@ -14,8 +14,8 @@ flutter::ExternalViewEmbedder* Surface::GetExternalViewEmbedder() {
   return nullptr;
 }
 
-bool Surface::MakeRenderContextCurrent() {
-  return true;
+std::unique_ptr<GLContextResult> Surface::MakeRenderContextCurrent() {
+  return std::make_unique<GLContextDefaultResult>(true);
 }
 
 }  // namespace flutter

shell/common/surface.h

@@ -31,7 +31,7 @@ class Surface {
 
   virtual flutter::ExternalViewEmbedder* GetExternalViewEmbedder();
 
-  virtual bool MakeRenderContextCurrent();
+  virtual std::unique_ptr<GLContextResult> MakeRenderContextCurrent();
 
  private:
   FML_DISALLOW_COPY_AND_ASSIGN(Surface);

shell/common/surface_frame.cc

@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/common/surface_frame.h"
-
 #include "flutter/fml/logging.h"
 
 namespace flutter {
@@ -17,6 +16,18 @@ SurfaceFrame::SurfaceFrame(sk_sp<SkSurface> surface,
   FML_DCHECK(submit_callback_);
 }
 
+SurfaceFrame::SurfaceFrame(sk_sp<SkSurface> surface,
+                           bool supports_readback,
+                           const SubmitCallback& submit_callback,
+                           std::unique_ptr<GLContextResult> context_result)
+    : submitted_(false),
+      surface_(surface),
+      supports_readback_(supports_readback),
+      submit_callback_(submit_callback),
+      context_result_(std::move(context_result)) {
+  FML_DCHECK(submit_callback_);
+}
+
 SurfaceFrame::~SurfaceFrame() {
   if (submit_callback_ && !submitted_) {
     // Dropping without a Submit.

shell/common/surface_frame.h

@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "flutter/fml/macros.h"
+#include "flutter/shell/common/gl_context_switch.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
@@ -24,6 +25,11 @@ class SurfaceFrame {
                bool supports_readback,
                const SubmitCallback& submit_callback);
 
+  SurfaceFrame(sk_sp<SkSurface> surface,
+               bool supports_readback,
+               const SubmitCallback& submit_callback,
+               std::unique_ptr<GLContextResult> context_result);
+
   ~SurfaceFrame();
 
   bool Submit();
@@ -41,6 +47,7 @@ class SurfaceFrame {
   sk_sp<SkSurface> surface_;
   bool supports_readback_;
   SubmitCallback submit_callback_;
+  std::unique_ptr<GLContextResult> context_result_;
 
   bool PerformSubmit();
 

shell/gpu/BUILD.gn

@@ -11,6 +11,7 @@ gpu_common_deps = [
   "//flutter/flow",
   "//flutter/fml",
   "//flutter/shell/common",
+  "//flutter/shell/common:common_standalone",
   "//third_party/skia",
 ]
 

shell/gpu/gpu_surface_gl.cc

@@ -39,7 +39,8 @@ GPUSurfaceGL::GPUSurfaceGL(GPUSurfaceGLDelegate* delegate,
     : delegate_(delegate),
       render_to_surface_(render_to_surface),
       weak_factory_(this) {
-  if (!delegate_->GLContextMakeCurrent()) {
+  auto context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetResult()) {
     FML_LOG(ERROR)
         << "Could not make the context current to setup the gr context.";
     return;
@@ -98,7 +99,8 @@ GPUSurfaceGL::GPUSurfaceGL(sk_sp<GrContext> gr_context,
       context_(gr_context),
       render_to_surface_(render_to_surface),
       weak_factory_(this) {
-  if (!delegate_->GLContextMakeCurrent()) {
+  auto context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetResult()) {
     FML_LOG(ERROR)
         << "Could not make the context current to setup the gr context.";
     return;
@@ -114,8 +116,8 @@ GPUSurfaceGL::~GPUSurfaceGL() {
   if (!valid_) {
     return;
   }
-
-  if (!delegate_->GLContextMakeCurrent()) {
+  auto context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetResult()) {
     FML_LOG(ERROR) << "Could not make the context current to destroy the "
                       "GrContext resources.";
     return;
@@ -229,8 +231,8 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGL::AcquireFrame(const SkISize& size) {
   if (delegate_ == nullptr) {
     return nullptr;
   }
-
-  if (!delegate_->GLContextMakeCurrent()) {
+  auto context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetResult()) {
     FML_LOG(ERROR)
         << "Could not make the context current to acquire the frame.";
     return nullptr;
@@ -255,7 +257,6 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGL::AcquireFrame(const SkISize& size) {
   }
 
   surface->getCanvas()->setMatrix(root_surface_transformation);
-
   SurfaceFrame::SubmitCallback submit_callback =
       [weak = weak_factory_.GetWeakPtr()](const SurfaceFrame& surface_frame,
                                           SkCanvas* canvas) {
@@ -263,7 +264,8 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGL::AcquireFrame(const SkISize& size) {
       };
 
   return std::make_unique<SurfaceFrame>(
-      surface, delegate_->SurfaceSupportsReadback(), submit_callback);
+      surface, delegate_->SurfaceSupportsReadback(), submit_callback,
+      std::move(context_switch));
 }
 
 bool GPUSurfaceGL::PresentSurface(SkCanvas* canvas) {
@@ -329,7 +331,7 @@ flutter::ExternalViewEmbedder* GPUSurfaceGL::GetExternalViewEmbedder() {
 }
 
 // |Surface|
-bool GPUSurfaceGL::MakeRenderContextCurrent() {
+std::unique_ptr<GLContextResult> GPUSurfaceGL::MakeRenderContextCurrent() {
   return delegate_->GLContextMakeCurrent();
 }
 

shell/gpu/gpu_surface_gl.h

@@ -11,6 +11,7 @@
 #include "flutter/flow/embedded_views.h"
 #include "flutter/fml/macros.h"
 #include "flutter/fml/memory/weak_ptr.h"
+#include "flutter/shell/common/gl_context_switch.h"
 #include "flutter/shell/common/surface.h"
 #include "flutter/shell/gpu/gpu_surface_gl_delegate.h"
 #include "third_party/skia/include/gpu/GrContext.h"
@@ -45,7 +46,7 @@ class GPUSurfaceGL : public Surface {
   flutter::ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
   // |Surface|
-  bool MakeRenderContextCurrent() override;
+  std::unique_ptr<GLContextResult> MakeRenderContextCurrent() override;
 
  private:
   GPUSurfaceGLDelegate* delegate_;

shell/gpu/gpu_surface_gl_delegate.h

@@ -7,6 +7,7 @@
 
 #include "flutter/flow/embedded_views.h"
 #include "flutter/fml/macros.h"
+#include "flutter/shell/common/gl_context_switch.h"
 #include "flutter/shell/gpu/gpu_surface_delegate.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/gpu/gl/GrGLInterface.h"
@@ -21,7 +22,7 @@ class GPUSurfaceGLDelegate : public GPUSurfaceDelegate {
   ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
   // Called to make the main GL context current on the current thread.
-  virtual bool GLContextMakeCurrent() = 0;
+  virtual std::unique_ptr<GLContextResult> GLContextMakeCurrent() = 0;
 
   // Called to clear the current GL context on the thread. This may be called on
   // either the GPU or IO threads.

shell/gpu/gpu_surface_metal.h

@@ -50,7 +50,7 @@ class GPUSurfaceMetal : public Surface {
   flutter::ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
   // |Surface|
-  bool MakeRenderContextCurrent() override;
+  std::unique_ptr<GLContextResult> MakeRenderContextCurrent() override;
 
   void ReleaseUnusedDrawableIfNecessary();
 

shell/gpu/gpu_surface_metal.mm

@@ -127,9 +127,9 @@ flutter::ExternalViewEmbedder* GPUSurfaceMetal::GetExternalViewEmbedder() {
 }
 
 // |Surface|
-bool GPUSurfaceMetal::MakeRenderContextCurrent() {
+std::unique_ptr<GLContextResult> GPUSurfaceMetal::MakeRenderContextCurrent() {
   // This backend has no such concept.
-  return true;
+  return std::make_unique<GLContextDefaultResult>(true);
 }
 
 void GPUSurfaceMetal::ReleaseUnusedDrawableIfNecessary() {

shell/platform/android/android_surface_gl.cc

@@ -106,9 +106,11 @@ bool AndroidSurfaceGL::SetNativeWindow(
   return true;
 }
 
-bool AndroidSurfaceGL::GLContextMakeCurrent() {
+std::unique_ptr<GLContextResult> AndroidSurfaceGL::GLContextMakeCurrent() {
   FML_DCHECK(onscreen_context_ && onscreen_context_->IsValid());
-  return onscreen_context_->MakeCurrent();
+  auto default_context_result = std::make_unique<GLContextDefaultResult>(
+      onscreen_context_->MakeCurrent());
+  return std::move(default_context_result);
 }
 
 bool AndroidSurfaceGL::GLContextClearCurrent() {

shell/platform/android/android_surface_gl.h

@@ -48,7 +48,7 @@ class AndroidSurfaceGL final : public GPUSurfaceGLDelegate,
   bool SetNativeWindow(fml::RefPtr<AndroidNativeWindow> window) override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<GLContextResult> GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;

shell/platform/darwin/ios/BUILD.gn

@@ -98,6 +98,8 @@ source_set("flutter_framework_source") {
     "ios_surface_gl.mm",
     "ios_surface_software.h",
     "ios_surface_software.mm",
+    "ios_switchable_gl_context.h",
+    "ios_switchable_gl_context.mm",
     "platform_view_ios.h",
     "platform_view_ios.mm",
     "rendering_api_selection.h",
@@ -130,6 +132,7 @@ source_set("flutter_framework_source") {
     "//flutter/runtime",
     "//flutter/runtime:libdart",
     "//flutter/shell/common",
+    "//flutter/shell/common:common_standalone",
     "//flutter/shell/platform/darwin/common",
     "//flutter/shell/platform/darwin/common:framework_shared",
     "//flutter/shell/profiling:profiling",

shell/platform/darwin/ios/ios_context.h

@@ -10,6 +10,7 @@
 #include "flutter/flow/texture.h"
 #include "flutter/fml/macros.h"
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
+#include "flutter/shell/common/gl_context_switch.h"
 #include "flutter/shell/platform/darwin/common/framework/Headers/FlutterTexture.h"
 #include "flutter/shell/platform/darwin/ios/rendering_api_selection.h"
 #include "third_party/skia/include/gpu/GrContext.h"
@@ -84,9 +85,12 @@ class IOSContext {
   /// @attention  Only one context may be bound to a thread at any given time.
   ///             Making a binding on a thread, clears the old binding.
   ///
-  /// @return     If the on-screen context could be bound to the current thread.
+  /// @return     A GLContextResult that represents the result of the method.
+  ///             The GetResult() returns a bool that indicates If the on-screen context could be
+  ///             bound to the current
+  /// thread.
   ///
-  virtual bool MakeCurrent() = 0;
+  virtual std::unique_ptr<GLContextResult> MakeCurrent() = 0;
 
   //----------------------------------------------------------------------------
   /// @brief      Creates an external texture proxy of the appropriate client

shell/platform/darwin/ios/ios_context_gl.h

@@ -9,6 +9,7 @@
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
 #include "flutter/shell/common/platform_view.h"
 #include "flutter/shell/platform/darwin/ios/ios_context.h"
+#include "flutter/shell/platform/darwin/ios/ios_context_gl.h"
 #include "flutter/shell/platform/darwin/ios/ios_render_target_gl.h"
 
 @class CAEAGLLayer;
@@ -32,7 +33,7 @@ class IOSContextGL final : public IOSContext {
   sk_sp<GrContext> CreateResourceContext() override;
 
   // |IOSContext|
-  bool MakeCurrent() override;
+  std::unique_ptr<GLContextResult> MakeCurrent() override;
 
   // |IOSContext|
   std::unique_ptr<Texture> CreateExternalTexture(

shell/platform/darwin/ios/ios_context_gl.mm

@@ -28,7 +28,7 @@ IOSContextGL::~IOSContextGL() = default;
 
 std::unique_ptr<IOSRenderTargetGL> IOSContextGL::CreateRenderTarget(
     fml::scoped_nsobject<CAEAGLLayer> layer) {
-  return std::make_unique<IOSRenderTargetGL>(std::move(layer), context_, resource_context_);
+  return std::make_unique<IOSRenderTargetGL>(std::move(layer), context_);
 }
 
 // |IOSContext|
@@ -44,8 +44,9 @@ sk_sp<GrContext> IOSContextGL::CreateResourceContext() {
 }
 
 // |IOSContext|
-bool IOSContextGL::MakeCurrent() {
-  return [EAGLContext setCurrentContext:context_.get()];
+std::unique_ptr<GLContextResult> IOSContextGL::MakeCurrent() {
+  return std::make_unique<GLContextSwitch>(
+      std::make_unique<IOSSwitchableGLContext>(context_.get()));
 }
 
 // |IOSContext|

shell/platform/darwin/ios/ios_context_metal.h

@@ -43,7 +43,7 @@ class IOSContextMetal final : public IOSContext {
   sk_sp<GrContext> CreateResourceContext() override;
 
   // |IOSContext|
-  bool MakeCurrent() override;
+  std::unique_ptr<GLContextResult> MakeCurrent() override;
 
   // |IOSContext|
   std::unique_ptr<Texture> CreateExternalTexture(

shell/platform/darwin/ios/ios_context_metal.mm

@@ -96,9 +96,9 @@ sk_sp<GrContext> IOSContextMetal::CreateResourceContext() {
 }
 
 // |IOSContext|
-bool IOSContextMetal::MakeCurrent() {
+std::unique_ptr<GLContextResult> IOSContextMetal::MakeCurrent() {
   // This only makes sense for context that need to be bound to a specific thread.
-  return true;
+  return std::make_unique<GLContextDefaultResult>(true);
 }
 
 // |IOSContext|

shell/platform/darwin/ios/ios_context_software.h

@@ -21,7 +21,7 @@ class IOSContextSoftware final : public IOSContext {
   sk_sp<GrContext> CreateResourceContext() override;
 
   // |IOSContext|
-  bool MakeCurrent() override;
+  std::unique_ptr<GLContextResult> MakeCurrent() override;
 
   // |IOSContext|
   std::unique_ptr<Texture> CreateExternalTexture(

shell/platform/darwin/ios/ios_context_software.mm

@@ -17,8 +17,9 @@ sk_sp<GrContext> IOSContextSoftware::CreateResourceContext() {
 }
 
 // |IOSContext|
-bool IOSContextSoftware::MakeCurrent() {
-  return false;
+std::unique_ptr<GLContextResult> IOSContextSoftware::MakeCurrent() {
+  // This only makes sense for context that need to be bound to a specific thread.
+  return std::make_unique<GLContextDefaultResult>(false);
 }
 
 // |IOSContext|

shell/platform/darwin/ios/ios_render_target_gl.h

@@ -13,14 +13,14 @@
 #include "flutter/fml/macros.h"
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
 #include "flutter/shell/common/platform_view.h"
+#include "flutter/shell/platform/darwin/ios/ios_switchable_gl_context.h"
 
 namespace flutter {
 
 class IOSRenderTargetGL {
  public:
   IOSRenderTargetGL(fml::scoped_nsobject<CAEAGLLayer> layer,
-                    fml::scoped_nsobject<EAGLContext> context,
-                    fml::scoped_nsobject<EAGLContext> resource_context);
+                    fml::scoped_nsobject<EAGLContext> context_);
 
   ~IOSRenderTargetGL();
 
@@ -35,7 +35,6 @@ class IOSRenderTargetGL {
  private:
   fml::scoped_nsobject<CAEAGLLayer> layer_;
   fml::scoped_nsobject<EAGLContext> context_;
-  fml::scoped_nsobject<EAGLContext> resource_context_;
   GLuint framebuffer_ = GL_NONE;
   GLuint colorbuffer_ = GL_NONE;
   GLint storage_size_width_ = GL_NONE;

shell/platform/darwin/ios/ios_render_target_gl.mm

@@ -13,20 +13,16 @@
 namespace flutter {
 
 IOSRenderTargetGL::IOSRenderTargetGL(fml::scoped_nsobject<CAEAGLLayer> layer,
-                                     fml::scoped_nsobject<EAGLContext> context,
-                                     fml::scoped_nsobject<EAGLContext> resource_context)
-    : layer_(std::move(layer)),
-      context_(std::move(context)),
-      resource_context_(std::move(resource_context)) {
+                                     fml::scoped_nsobject<EAGLContext> context)
+    : layer_(std::move(layer)), context_(context) {
   FML_DCHECK(layer_ != nullptr);
   FML_DCHECK(context_ != nullptr);
-  FML_DCHECK(resource_context_ != nullptr);
 
   if (@available(iOS 9.0, *)) {
     [layer_ setPresentsWithTransaction:YES];
   }
-
-  bool context_current = [EAGLContext setCurrentContext:context_];
+  auto context_switch = GLContextSwitch(std::make_unique<IOSSwitchableGLContext>(context_.get()));
+  bool context_current = context_switch.GetResult();
 
   FML_DCHECK(context_current);
   FML_DCHECK(glGetError() == GL_NO_ERROR);
@@ -61,8 +57,7 @@ IOSRenderTargetGL::IOSRenderTargetGL(fml::scoped_nsobject<CAEAGLLayer> layer,
 }
 
 IOSRenderTargetGL::~IOSRenderTargetGL() {
-  EAGLContext* context = EAGLContext.currentContext;
-  [EAGLContext setCurrentContext:context_];
+  auto context_switch = GLContextSwitch(std::make_unique<IOSSwitchableGLContext>(context_.get()));
   FML_DCHECK(glGetError() == GL_NO_ERROR);
 
   // Deletes on GL_NONEs are ignored
@@ -70,11 +65,6 @@ IOSRenderTargetGL::~IOSRenderTargetGL() {
   glDeleteRenderbuffers(1, &colorbuffer_);
 
   FML_DCHECK(glGetError() == GL_NO_ERROR);
-  if (context == context_.get()) {
-    [EAGLContext setCurrentContext:nil];
-  } else {
-    [EAGLContext setCurrentContext:context];
-  }
 }
 
 // |IOSRenderTarget|
@@ -118,7 +108,8 @@ bool IOSRenderTargetGL::UpdateStorageSizeIfNecessary() {
 
   FML_DCHECK(glGetError() == GL_NO_ERROR);
 
-  if (![EAGLContext setCurrentContext:context_]) {
+  auto context_switch = GLContextSwitch(std::make_unique<IOSSwitchableGLContext>(context_.get()));
+  if (!context_switch.GetResult()) {
     return false;
   }
 
@@ -129,7 +120,8 @@ bool IOSRenderTargetGL::UpdateStorageSizeIfNecessary() {
   glBindRenderbuffer(GL_RENDERBUFFER, colorbuffer_);
   FML_DCHECK(glGetError() == GL_NO_ERROR);
 
-  if (![context_.get() renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer_.get()]) {
+  auto current_context = [EAGLContext currentContext];
+  if (![current_context renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer_.get()]) {
     return false;
   }
 

shell/platform/darwin/ios/ios_surface_gl.h

@@ -34,7 +34,7 @@ class IOSSurfaceGL final : public IOSSurface, public GPUSurfaceGLDelegate {
   std::unique_ptr<Surface> CreateGPUSurface(GrContext* gr_context) override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<GLContextResult> GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;

shell/platform/darwin/ios/ios_surface_gl.mm

@@ -59,16 +59,20 @@ bool IOSSurfaceGL::SurfaceSupportsReadback() const {
 }
 
 // |GPUSurfaceGLDelegate|
-bool IOSSurfaceGL::GLContextMakeCurrent() {
+std::unique_ptr<GLContextResult> IOSSurfaceGL::GLContextMakeCurrent() {
   if (!IsValid()) {
-    return false;
+    return std::make_unique<GLContextDefaultResult>(false);
   }
-  return render_target_->UpdateStorageSizeIfNecessary() && GetContext()->MakeCurrent();
+  bool update_if_necessary = render_target_->UpdateStorageSizeIfNecessary();
+  if (!update_if_necessary) {
+    return std::make_unique<GLContextDefaultResult>(false);
+  }
+  return GetContext()->MakeCurrent();
 }
 
 // |GPUSurfaceGLDelegate|
 bool IOSSurfaceGL::GLContextClearCurrent() {
-  [EAGLContext setCurrentContext:nil];
+  // |GLContextMakeCurrent| should handle the scope of the gl context.
   return true;
 }
 

shell/platform/darwin/ios/ios_switchable_gl_context.h

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_DARWIN_IOS_IOS_SWITCHABLE_GL_CONTEXT_H_
+#define FLUTTER_SHELL_PLATFORM_DARWIN_IOS_IOS_SWITCHABLE_GL_CONTEXT_H_
+
+#include "flutter/fml/macros.h"
+#include "flutter/fml/memory/thread_checker.h"
+#include "flutter/fml/memory/weak_ptr.h"
+#include "flutter/shell/common/gl_context_switch.h"
+
+@class EAGLContext;
+
+namespace flutter {
+
+//------------------------------------------------------------------------------
+/// The iOS implementation of a |SwitchableGLContext|.
+///
+/// It wraps a pointer to an EAGLContext. When passed in the constructor of the |GLContextSwitch|,
+/// this EAGLContext is set to current. When the |GLContextSwitch| destroys, the current context
+/// will be restored to the context before setting this EAGLContext to current.
+///
+/// Note: An |IOSSwitchableGLContext| doesn't retain the EAGLContext. Someone else must retain the
+/// pointer and outlive all the |IOSSwitchableGLContext|. This object is meant to be only owned by a
+/// |GLContextSwitch| and should be destroyed when The |GLContectSwitch| destroys.
+class IOSSwitchableGLContext final : public SwitchableGLContext {
+ public:
+  IOSSwitchableGLContext(EAGLContext* context);
+
+  bool SetCurrent() override;
+
+  bool RemoveCurrent() override;
+
+ private:
+  // These pointers are managed by IOSRendererTarget/IOSContextGL or a 3rd party
+  // plugin that uses gl context. |IOSSwitchableGLContext| should never outlive
+  // those objects. Never release this pointer within this object.
+  EAGLContext* context_;
+  EAGLContext* previous_context_;
+
+  FML_DECLARE_THREAD_CHECKER(checker);
+
+  FML_DISALLOW_COPY_AND_ASSIGN(IOSSwitchableGLContext);
+};
+
+}  // namespace flutter
+
+#endif

shell/platform/darwin/ios/ios_switchable_gl_context.mm

+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/darwin/ios/ios_switchable_gl_context.h"
+#import <OpenGLES/EAGL.h>
+
+namespace flutter {
+
+IOSSwitchableGLContext::IOSSwitchableGLContext(EAGLContext* context) : context_(context){};
+
+bool IOSSwitchableGLContext::SetCurrent() {
+  FML_DCHECK_CREATION_THREAD_IS_CURRENT(checker);
+  FML_DCHECK(context_ != nullptr);
+  EAGLContext* current_context = EAGLContext.currentContext;
+  previous_context_ = current_context;
+  return [EAGLContext setCurrentContext:context_];
+};
+
+bool IOSSwitchableGLContext::RemoveCurrent() {
+  FML_DCHECK_CREATION_THREAD_IS_CURRENT(checker);
+  return [EAGLContext setCurrentContext:previous_context_];
+};
+}

shell/platform/embedder/embedder_surface_gl.cc

@@ -34,8 +34,9 @@ bool EmbedderSurfaceGL::IsValid() const {
 }
 
 // |GPUSurfaceGLDelegate|
-bool EmbedderSurfaceGL::GLContextMakeCurrent() {
-  return gl_dispatch_table_.gl_make_current_callback();
+std::unique_ptr<GLContextResult> EmbedderSurfaceGL::GLContextMakeCurrent() {
+  return std::make_unique<GLContextDefaultResult>(
+      gl_dispatch_table_.gl_make_current_callback());
 }
 
 // |GPUSurfaceGLDelegate|

shell/platform/embedder/embedder_surface_gl.h

@@ -50,7 +50,7 @@ class EmbedderSurfaceGL final : public EmbedderSurface,
   sk_sp<GrContext> CreateResourceContext() const override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<GLContextResult> GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;