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

cc/blimp/layer_tree_host_remote.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_BLIMP_LAYER_TREE_HOST_REMOTE_H_
 #define CC_BLIMP_LAYER_TREE_HOST_REMOTE_H_
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "cc/base/cc_export.h"
@@ skipping 94 matching lines @@
   RemoteCompositorBridge* remote_compositor_bridge() const {
     return remote_compositor_bridge_.get();
   }
 
   virtual void DispatchDrawAndSwapCallbacks();
   void SetTaskRunnerProviderForTesting(
       std::unique_ptr<TaskRunnerProvider> task_runner_provider);
 
   // RemoteCompositorBridgeClient implementation.
   void BeginMainFrame() override;
+  bool ApplyScrollAndScaleUpdateFromClient(
+      const ScrollOffsetMap& client_scroll_map,
+      float client_page_scale) override;
 
  private:
   enum class FramePipelineStage { NONE, ANIMATE, UPDATE_LAYERS, COMMIT };
 
   void MainFrameRequested(FramePipelineStage requested_pipeline_stage);
   void ScheduleMainFrameIfNecessary();
   void MainFrameComplete();
   void SerializeCurrentState(proto::LayerTreeHost* layer_tree_host_proto);
 
   const int id_;
   int source_frame_number_ = 0;
   bool visible_ = false;
   bool defer_commits_ = false;
 
+  // In threaded/single-threaded mode, the LayerTree and Layers expect scroll/
+  // scale updates to come from the impl thread only during the main frame.
+  // Since we synchronize state outside of that, this is set so we can
+  // temporarily report that a commit is in progress.
+  bool synchronizing_client_updates_ = false;
+
   // Set to true if a main frame request is pending on the
   // RemoteCompositorBridge.
   bool main_frame_requested_from_bridge_ = false;
 
   // Set to the pipeline stage we are currently at if we are inside a main frame
   // update.
   FramePipelineStage current_pipeline_stage_ = FramePipelineStage::NONE;
 
   // Set to the pipeline stage we need to go to for the current main frame
   // update, if we are inside a main frame update.
@@ skipping 25 matching lines @@
   SurfaceSequenceGenerator surface_sequence_generator_;
 
   base::WeakPtr<InputHandler> input_handler_weak_ptr_;
 
   base::WeakPtrFactory<LayerTreeHostRemote> weak_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_BLIMP_LAYER_TREE_HOST_REMOTE_H_