cc/blimp: Set up hooks for scroll/scale sync.

cc/test/layer_tree_host_remote_for_testing.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_TEST_LAYER_TREE_HOST_REMOTE_FOR_TESTING_H_
 #define CC_TEST_LAYER_TREE_HOST_REMOTE_FOR_TESTING_H_
 
 #include "base/macros.h"
 #include "cc/blimp/compositor_state_deserializer_client.h"
 #include "cc/blimp/layer_tree_host_remote.h"
+#include "ui/gfx/geometry/scroll_offset.h"
 
 namespace gpu {
 class GpuMemoryBufferManager;
 }  // namespace gpu
 
 namespace cc {
 class CompositorStateDeserializer;
 class FakeImageSerializationProcessor;
 class LayerTreeHostInProcess;
 class SharedBitmapManager;
@@ skipping 61 matching lines @@
 
   // CompositorStateDeserializerClient implementation.
   bool ShouldRetainClientScroll(int engine_layer_id,
                                 const gfx::ScrollOffset& new_offset) override;
   bool ShouldRetainClientPageScale(float new_page_scale) override;
 
   // LayerTreeHostRemote interface.
   void DispatchDrawAndSwapCallbacks() override;
 
   void LayerDidScroll(int engine_layer_id);
+  void ApplyUpdatesFromInProcessHost();
 
   void RemoteHostNeedsMainFrame();
   void ProcessRemoteCompositorUpdate(
       std::unique_ptr<CompositorProtoState> compositor_proto_state);
   void UpdateStateOnInProcessHost();
 
   std::unique_ptr<LayerTreeHostInProcess> layer_tree_host_in_process_;
   std::unique_ptr<CompositorStateDeserializer> compositor_state_deserializer_;
 
   std::unique_ptr<CompositorProtoState> pending_compositor_proto_state_;
+  ScrollOffsetMap layers_scrolled_;
 
   std::unique_ptr<LayerTreeHostInProcessClient>
       layer_tree_host_in_process_client_;
 
   std::unique_ptr<FakeImageSerializationProcessor>
       image_serialization_processor_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostRemoteForTesting);
 };
 
 }  // namespace cc
 
 #endif  // CC_TEST_LAYER_TREE_HOST_REMOTE_FOR_TESTING_H_