Don't export embedder API in desktop embeddings (#18735)

The embedder.h API layer is an implementation detail of the desktop
embeddings, not part of the public API surface, so should not be part of
the public symbol list for those libraries.

shell/platform/common/cpp/BUILD.gn

@@ -67,7 +67,7 @@ source_set("common_cpp") {
   deps = [
     ":common_cpp_library_headers",
     "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
-    "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
   ]
 
   public_deps = [

shell/platform/darwin/macos/BUILD.gn

@@ -70,7 +70,7 @@ source_set("flutter_framework_source") {
 
   deps = [
     "//flutter/shell/platform/darwin/common:framework_shared",
-    "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
   ]
 
   public_configs = [ "//flutter:config" ]
@@ -115,7 +115,7 @@ executable("flutter_desktop_darwin_unittests") {
     ":flutter_desktop_darwin_fixtures",
     ":flutter_framework_source",
     "//flutter/shell/platform/darwin/common:framework_shared",
-    "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
     "//flutter/testing",
     "//flutter/testing:dart",
     "//flutter/testing:skia",

shell/platform/embedder/BUILD.gn

@@ -86,8 +86,8 @@ embedder_source_set("embedder") {
   public_configs = []
 }
 
-embedder_source_set("embedder_with_symbol_prefix") {
-  public_configs = [ ":embedder_prefix_config" ]
+embedder_source_set("embedder_as_internal_library") {
+  public_configs = [ ":embedder_internal_library_config" ]
 }
 
 source_set("embedder_headers") {
@@ -98,8 +98,16 @@ source_set("embedder_headers") {
   public_configs = [ "//flutter:config" ]
 }
 
-config("embedder_prefix_config") {
-  defines = [ "FLUTTER_API_SYMBOL_PREFIX=Embedder" ]
+# For using the embedder API as internal implementation detail of an
+# embedding.
+config("embedder_internal_library_config") {
+  defines = [
+    # Use prefixed symbols to avoid collisions with higher level API.
+    "FLUTTER_API_SYMBOL_PREFIX=Embedder",
+
+    # Don't export the embedder.h API surface.
+    "FLUTTER_NO_EXPORT",
+  ]
 }
 
 test_fixtures("fixtures") {

shell/platform/embedder/embedder.cc

@@ -14,11 +14,13 @@
 #include "third_party/dart/runtime/bin/elf_loader.h"
 #include "third_party/dart/runtime/include/dart_native_api.h"
 
+#if !defined(FLUTTER_NO_EXPORT)
 #if OS_WIN
 #define FLUTTER_EXPORT __declspec(dllexport)
 #else  // OS_WIN
 #define FLUTTER_EXPORT __attribute__((visibility("default")))
 #endif  // OS_WIN
+#endif  // !FLUTTER_NO_EXPORT
 
 extern "C" {
 #if FLUTTER_RUNTIME_MODE == FLUTTER_RUNTIME_MODE_DEBUG

shell/platform/glfw/BUILD.gn

@@ -55,7 +55,7 @@ source_set("flutter_glfw") {
     "//flutter/shell/platform/common/cpp:common_cpp",
     "//flutter/shell/platform/common/cpp:common_cpp_input",
     "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
-    "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
     "//flutter/shell/platform/glfw/client_wrapper:client_wrapper_glfw",
     "//third_party/rapidjson",
   ]

shell/platform/linux/BUILD.gn

@@ -123,7 +123,7 @@ source_set("flutter_linux") {
   ]
 
   deps = [
-    "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
   ]
 }
 

shell/platform/windows/BUILD.gn

@@ -74,7 +74,7 @@ source_set("flutter_windows_source") {
     "//flutter/shell/platform/common/cpp:common_cpp",
     "//flutter/shell/platform/common/cpp:common_cpp_input",
     "//flutter/shell/platform/common/cpp/client_wrapper:client_wrapper",
-    "//flutter/shell/platform/embedder:embedder_with_symbol_prefix",
+    "//flutter/shell/platform/embedder:embedder_as_internal_library",
     "//flutter/shell/platform/windows/client_wrapper:client_wrapper_windows",
     "//third_party/angle:libEGL_static",  # the order of libEGL_static and libGLESv2_static is important.. if reversed, will cause a linker error DllMain already defined in LIBCMTD.lib
     "//third_party/angle:libGLESv2_static",