From 7b612b0f2f7abd8e51e3ee6bf7d19e0d2d84ea77 Mon Sep 17 00:00:00 2001
From: Chinmay Garde <chinmaygarde@gmail.com>
Date: Wed, 15 Jun 2016 11:02:17 -0700
Subject: [PATCH] iOS: Discard the depth and stencil attachments of the
 framebuffer before presenting the color renderbuffer. (#2737)

---
 flow/instrumentation.cc | 2 +-
 ui/gl/gl_surface_ios.mm | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/flow/instrumentation.cc b/flow/instrumentation.cc
index 9cfacdd6d1..bdabde74de 100644
--- a/flow/instrumentation.cc
+++ b/flow/instrumentation.cc
@@ -71,7 +71,7 @@ void Stopwatch::Visualize(SkCanvas& canvas, const SkRect& rect) const {
   const SkScalar bottom = y + height;
   const SkScalar right = x + width;
 
-  // Scale the graph to show frame times up to those that are 4 times the frame time.
+  // Scale the graph to show frame times up to those that are 3 times the frame time.
   const double max_interval = kOneFrameMS * 3.0;
   const double max_unit_interval = UnitFrameInterval(max_interval);
 
diff --git a/ui/gl/gl_surface_ios.mm b/ui/gl/gl_surface_ios.mm
index a4354f8fcc..c4ca982c9c 100644
--- a/ui/gl/gl_surface_ios.mm
+++ b/ui/gl/gl_surface_ios.mm
@@ -216,6 +216,14 @@ void GLSurfaceIOS::SetupFramebufferIfNecessary() {
 }
 
 bool GLSurfaceIOS::SwapBuffers() {
+  const GLenum discards[] = {
+    GL_DEPTH_ATTACHMENT,
+    GL_STENCIL_ATTACHMENT,
+  };
+
+  glDiscardFramebufferEXT(GL_FRAMEBUFFER, sizeof(discards) / sizeof(GLenum),
+                          discards);
+
   glBindRenderbuffer(GL_RENDERBUFFER, colorbuffer_);
   return [[EAGLContext currentContext] presentRenderbuffer:GL_RENDERBUFFER];
 }
-- 
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