Remove offscreen compositor contexts.

cc/trees/layer_tree_host_impl.h

Index: cc/trees/layer_tree_host_impl.h
diff --git a/cc/trees/layer_tree_host_impl.h b/cc/trees/layer_tree_host_impl.h
index a1f4fae0a4f3901f0890c361f74a0c67b8dc62a0..c503806a5803aec777f3c7d609d48a48f92af264 100644
--- a/cc/trees/layer_tree_host_impl.h
+++ b/cc/trees/layer_tree_host_impl.h
@@ -222,8 +222,7 @@ class CC_EXPORT LayerTreeHostImpl
   virtual void NotifyReadyToActivate() OVERRIDE;
 
   // OutputSurfaceClient implementation.
-  virtual bool DeferredInitialize(
-      scoped_refptr<ContextProvider> offscreen_context_provider) OVERRIDE;
+  virtual void DeferredInitialize() OVERRIDE;
   virtual void ReleaseGL() OVERRIDE;
   virtual void SetNeedsRedrawRect(const gfx::Rect& rect) OVERRIDE;
   virtual void BeginFrame(const BeginFrameArgs& args) OVERRIDE;
@@ -247,12 +246,6 @@ class CC_EXPORT LayerTreeHostImpl
   bool CanDraw() const;
   OutputSurface* output_surface() const { return output_surface_.get(); }
 
-  void SetOffscreenContextProvider(
-      const scoped_refptr<ContextProvider>& offscreen_context_provider);
-  ContextProvider* offscreen_context_provider() const {
-    return offscreen_context_provider_.get();
-  }
-
   std::string LayerTreeAsJson() const;
 
   void FinishAllRendering();