Finish the rename from cc::GraphicsContext to cc::OutputSurface

cc/layer_impl.h

Index: cc/layer_impl.h
diff --git a/cc/layer_impl.h b/cc/layer_impl.h
index c39cd6da54ab73f0c139420874daed59f33898ed..3e642334365e2618f8bdb75becbf9586bea82a2f 100644
--- a/cc/layer_impl.h
+++ b/cc/layer_impl.h
@@ -262,10 +262,10 @@ public:
 
     virtual void didUpdateTransforms() { }
 
-    // Indicates that the context previously used to render this layer
+    // Indicates that the surface previously used to render this layer
     // was lost and that a new one has been created. Won't be called
-    // until the new context has been created successfully.
-    virtual void didLoseContext();
+    // until the new surface has been created successfully.
+    virtual void didLoseOutputSurface();
 
     ScrollbarAnimationController* scrollbarAnimationController() const { return m_scrollbarAnimationController.get(); }