cc: Add OutputSurface state snapshots.

cc/output/direct_renderer.h

Index: cc/output/direct_renderer.h
diff --git a/cc/output/direct_renderer.h b/cc/output/direct_renderer.h
index d08d58d59e71297435ad048252eaea9b8f9e6142..18646fccfafe40fbf7224705a7d58fcad84f2c63 100644
--- a/cc/output/direct_renderer.h
+++ b/cc/output/direct_renderer.h
@@ -63,6 +63,9 @@ class CC_EXPORT DirectRenderer {
   virtual void SwapBuffersComplete() {}
   virtual void DidReceiveTextureInUseResponses(
       const gpu::TextureInUseResponses& responses) {}
+  virtual void ReadbackSwappedOverlayTextures(
+      std::vector<SkBitmap>* bitmaps,
+      const base::Callback<void(bool)>& callback);
 
   // Allow tests to enlarge the texture size of non-root render passes to
   // verify cases where the texture doesn't match the render pass size.