Early terminate WebGL markContextChanged calls when appropriate

third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp

Index: third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
diff --git a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
index 31ab2ee44c267829bc361ecc0f752c2ae9c75e4c..5abb5c06c89280f6f5c428f2f527fb334ea2965a 100644
--- a/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
+++ b/third_party/WebKit/Source/modules/webgl/WebGLRenderingContextBase.cpp
@@ -1334,7 +1334,9 @@ void WebGLRenderingContextBase::markContextChanged(
   if (m_framebufferBinding || isContextLost())
     return;
 
-  drawingBuffer()->markContentsChanged();
+  if (!drawingBuffer()->markContentsChanged() && m_markedCanvasDirty) {

[Ken Russell (switch to Gerrit), 2016/11/29 04:31:16]

We should really revisit and clean up the maintenance of m_markedCanvasDirty,
which seems to only be set to false on the software compositing path.

+    return;
+  }
 
   if (!canvas())
     return;