cc/blimp: Add synchronization for scroll/scale state.

cc/test/layer_tree_host_remote_for_testing.h

Index: cc/test/layer_tree_host_remote_for_testing.h
diff --git a/cc/test/layer_tree_host_remote_for_testing.h b/cc/test/layer_tree_host_remote_for_testing.h
index 2af67222c216ce9103ace73e0dd51907661702ee..3248341c013860297be1ebc0fc4d035d95e94964 100644
--- a/cc/test/layer_tree_host_remote_for_testing.h
+++ b/cc/test/layer_tree_host_remote_for_testing.h
@@ -6,16 +6,14 @@
 #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/compositor_state_deserializer.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;
@@ -81,15 +79,12 @@ class LayerTreeHostRemoteForTesting : public LayerTreeHostRemote,
   class RemoteCompositorBridgeImpl;
 
   // CompositorStateDeserializerClient implementation.
-  bool ShouldRetainClientScroll(int engine_layer_id,
-                                const gfx::ScrollOffset& new_offset) override;
-  bool ShouldRetainClientPageScale(float new_page_scale) override;
+  void DidUpdateLocalState() override;
 
   // LayerTreeHostRemote interface.
   void DispatchDrawAndSubmitCallbacks() override;
 
-  void LayerDidScroll(int engine_layer_id);
-  void ApplyUpdatesFromInProcessHost();
+  void BeginRemoteMainFrame();
 
   void RemoteHostNeedsMainFrame();
   void ProcessRemoteCompositorUpdate(
@@ -98,7 +93,7 @@ class LayerTreeHostRemoteForTesting : public LayerTreeHostRemote,
   std::unique_ptr<LayerTreeHostInProcess> layer_tree_host_in_process_;
   std::unique_ptr<CompositorStateDeserializer> compositor_state_deserializer_;
 
-  ScrollOffsetMap layers_scrolled_;
+  bool client_state_dirty_ = false;
 
   std::unique_ptr<LayerTreeHostInProcessClient>
       layer_tree_host_in_process_client_;