cc: Route offscreen context creation for compositor to the browser.

ui/compositor/compositor.h

Index: ui/compositor/compositor.h
diff --git a/ui/compositor/compositor.h b/ui/compositor/compositor.h
index aa773b25e7c330e3ad10c1908666fe60ed8e61e5..038233d291bb94be38436e53bf1079d3cf2c581a 100644
--- a/ui/compositor/compositor.h
+++ b/ui/compositor/compositor.h
@@ -67,6 +67,10 @@ class COMPOSITOR_EXPORT ContextFactory {
   // with all compositors.
   virtual WebKit::WebGraphicsContext3D* CreateOffscreenContext() = 0;
 
+  virtual WebKit::WebGraphicsContext3D* OffscreenContextForMainThread() = 0;
+  virtual WebKit::WebGraphicsContext3D*
+      OffscreenContextForCompositorThread() = 0;
+
   // Destroys per-compositor data.
   virtual void RemoveCompositor(Compositor* compositor) = 0;
 };
@@ -81,6 +85,10 @@ class COMPOSITOR_EXPORT DefaultContextFactory : public ContextFactory {
   virtual cc::OutputSurface* CreateOutputSurface(
       Compositor* compositor) OVERRIDE;
   virtual WebKit::WebGraphicsContext3D* CreateOffscreenContext() OVERRIDE;
+  virtual WebKit::WebGraphicsContext3D* OffscreenContextForMainThread()
+      OVERRIDE;
+  virtual WebKit::WebGraphicsContext3D* OffscreenContextForCompositorThread()
+      OVERRIDE;
   virtual void RemoveCompositor(Compositor* compositor) OVERRIDE;
 
   bool Initialize();
@@ -95,6 +103,9 @@ class COMPOSITOR_EXPORT DefaultContextFactory : public ContextFactory {
       bool offscreen);
 
   scoped_refptr<gfx::GLShareGroup> share_group_;
+  scoped_ptr<WebKit::WebGraphicsContext3D> test_offscreen_context_main_thread_;
+  scoped_ptr<WebKit::WebGraphicsContext3D>
+      test_offscreen_context_compositor_thread_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultContextFactory);
 };
@@ -261,6 +272,10 @@ class COMPOSITOR_EXPORT Compositor
   virtual scoped_ptr<cc::OutputSurface>
       createOutputSurface() OVERRIDE;
   virtual void didRecreateOutputSurface(bool success) OVERRIDE;
+  virtual WebKit::WebGraphicsContext3D*
+      OffscreenContext3dForMainThread() OVERRIDE;
+  virtual WebKit::WebGraphicsContext3D*
+      OffscreenContext3dForCompositorThread() OVERRIDE;
   virtual scoped_ptr<cc::InputHandler> createInputHandler() OVERRIDE;
   virtual void willCommit() OVERRIDE;
   virtual void didCommit() OVERRIDE;