cc: Delete channel abstraction between proxies.

cc/trees/proxy_main.h

 // Copyright 2015 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_TREES_PROXY_MAIN_H_
 #define CC_TREES_PROXY_MAIN_H_
 
 #include "base/macros.h"
 #include "cc/base/cc_export.h"
 #include "cc/input/browser_controls_state.h"
-#include "cc/trees/channel_main.h"
 #include "cc/trees/proxy.h"
 #include "cc/trees/proxy_common.h"
 
 namespace cc {
 
+class BeginFrameSource;
 class MutatorEvents;
-class ChannelMain;
+class CompletionEvent;
 class CompositorFrameSink;
 class LayerTreeHostInProcess;
 class LayerTreeMutator;
+class ProxyImpl;
 
 // This class aggregates all interactions that the impl side of the compositor
 // needs to have with the main side.
 // The class is created and lives on the main thread.
 class CC_EXPORT ProxyMain : public Proxy {
  public:
-  static std::unique_ptr<ProxyMain> CreateThreaded(
-      LayerTreeHostInProcess* layer_tree_host,
-      TaskRunnerProvider* task_runner_provider);
+  ProxyMain(LayerTreeHostInProcess* layer_tree_host,
+            TaskRunnerProvider* task_runner_provider);
 
   ~ProxyMain() override;
 
   // Commits between the main and impl threads are processed through a pipeline
   // with the following stages. For efficiency we can early out at any stage if
   // we decide that no further processing is necessary.
   enum CommitPipelineStage {
     NO_PIPELINE_STAGE,
     ANIMATE_PIPELINE_STAGE,
     UPDATE_LAYERS_PIPELINE_STAGE,
     COMMIT_PIPELINE_STAGE,
   };
 
   void DidReceiveCompositorFrameAck();
   void BeginMainFrameNotExpectedSoon();
   void DidCommitAndDrawFrame();
   void SetAnimationEvents(std::unique_ptr<MutatorEvents> events);
   void DidLoseCompositorFrameSink();
   void RequestNewCompositorFrameSink();
   void DidInitializeCompositorFrameSink(bool success);
   void DidCompletePageScaleAnimation();
   void BeginMainFrame(
       std::unique_ptr<BeginMainFrameAndCommitState> begin_main_frame_state);
 
-  ChannelMain* channel_main() const { return channel_main_.get(); }
   CommitPipelineStage max_requested_pipeline_stage() const {
     return max_requested_pipeline_stage_;
   }
   CommitPipelineStage current_pipeline_stage() const {
     return current_pipeline_stage_;
   }
   CommitPipelineStage final_pipeline_stage() const {
     return final_pipeline_stage_;
   }
 
- protected:
-  ProxyMain(LayerTreeHostInProcess* layer_tree_host,
-            TaskRunnerProvider* task_runner_provider);
-
  private:
-  friend class ProxyMainForTest;
-
   // Proxy implementation.
   bool IsStarted() const override;
   bool CommitToActiveTree() const override;
   void SetCompositorFrameSink(
       CompositorFrameSink* compositor_frame_sink) override;
   void SetVisible(bool visible) override;
   void SetNeedsAnimate() override;
   void SetNeedsUpdateLayers() override;
   void SetNeedsCommit() override;
   void SetNeedsRedraw(const gfx::Rect& damage_rect) override;
   void SetNextCommitWaitsForActivation() override;
   void NotifyInputThrottledUntilCommit() override;
   void SetDeferCommits(bool defer_commits) override;
   bool CommitRequested() const override;
   bool BeginMainFrameRequested() const override;
   void MainThreadHasStoppedFlinging() override;
   void Start() override;
   void Stop() override;
   bool SupportsImplScrolling() const override;
   void SetMutator(std::unique_ptr<LayerTreeMutator> mutator) override;
   bool MainFrameWillHappenForTesting() override;
   void ReleaseCompositorFrameSink() override;
   void UpdateBrowserControlsState(BrowserControlsState constraints,
                                   BrowserControlsState current,
                                   bool animate) override;
 
-  // This sets the channel used by ProxyMain to communicate with ProxyImpl.
-  void SetChannel(std::unique_ptr<ChannelMain> channel_main);
-
   // Returns |true| if the request was actually sent, |false| if one was
   // already outstanding.
   bool SendCommitRequestToImplThreadIfNeeded(
       CommitPipelineStage required_stage);
   bool IsMainThread() const;
+  bool IsImplThread() const;
+  base::SingleThreadTaskRunner* ImplThreadTaskRunner();
+
+  void InitializeOnImplThread(CompletionEvent* completion_event);
+  void DestroyProxyImplOnImplThread(CompletionEvent* completion_event);
 
   LayerTreeHostInProcess* layer_tree_host_;
 
   TaskRunnerProvider* task_runner_provider_;
 
   const int layer_tree_host_id_;
 
   // The furthest pipeline stage which has been requested for the next
   // commit.
   CommitPipelineStage max_requested_pipeline_stage_;
   // The commit pipeline stage that is currently being processed.
   CommitPipelineStage current_pipeline_stage_;
   // The commit pipeline stage at which processing for the current commit
   // will stop. Only valid while we are executing the pipeline (i.e.,
   // |current_pipeline_stage| is set to a pipeline stage).
   CommitPipelineStage final_pipeline_stage_;
 
   bool commit_waits_for_activation_;
 
   // Set when the Proxy is started using Proxy::Start() and reset when it is
   // stopped using Proxy::Stop().
   bool started_;
 
   bool defer_commits_;
 
-  std::unique_ptr<ChannelMain> channel_main_;
+  // ProxyImpl is created and destroyed on the impl thread, and should only be
+  // accessed on the impl thread.
+  // It is safe to use base::Unretained to post tasks to ProxyImpl on the impl
+  // thread, since we control its lifetime. Any tasks posted to it are bound to
+  // run before we destroy it on the impl thread.
+  std::unique_ptr<ProxyImpl> proxy_impl_;
+
+  base::WeakPtrFactory<ProxyMain> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyMain);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROXY_MAIN_H_