cc: Use the onscreen context to perform composited ganesh filters.

cc/output/gl_renderer.h

Index: cc/output/gl_renderer.h
diff --git a/cc/output/gl_renderer.h b/cc/output/gl_renderer.h
index e776082ee2403bfe5892b95be642a82f5170964e..48a993132b6a5cade590a959d9ce49a4d83da2c8 100644
--- a/cc/output/gl_renderer.h
+++ b/cc/output/gl_renderer.h
@@ -45,6 +45,8 @@ class ScopedEnsureFramebufferAllocation;
 // Class that handles drawing of composited render layers using GL.
 class CC_EXPORT GLRenderer : public DirectRenderer {
  public:
+  class ScopedUseGrContext;
+
   static scoped_ptr<GLRenderer> Create(
       RendererClient* client,
       const LayerTreeSettings* settings,
@@ -216,6 +218,8 @@ class CC_EXPORT GLRenderer : public DirectRenderer {
                       bool success);
 
   void ReinitializeGLState();
+  void RestoreGLState();
+  void RestoreFramebuffer(DrawingFrame* frame);
 
   virtual void DiscardBackbuffer() OVERRIDE;
   virtual void EnsureBackbuffer() OVERRIDE;