cc:: Add remote mode to the compositor

cc/trees/remote_channel_impl.h

Index: cc/trees/remote_channel_impl.h
diff --git a/cc/trees/remote_channel_impl.h b/cc/trees/remote_channel_impl.h
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+// 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_REMOTE_CHANNEL_IMPL_H_
+#define CC_TREES_REMOTE_CHANNEL_IMPL_H_
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "cc/base/cc_export.h"
+#include "cc/base/completion_event.h"
+#include "cc/raster/task_graph_runner.h"
+#include "cc/trees/channel_impl.h"
+#include "cc/trees/proxy_impl.h"
+#include "cc/trees/remote_proto_channel.h"
+
+namespace cc {
+class LayerTreeHost;
+class LayerTreeSettings;
+class RemoteChannelHost;
+
+namespace proto {
+class CompositorMessage;
+class CompositorMessageToImpl;
+class CompositorMessageToMain;
+class InitializeImpl;
+}
+
+// The ChannelImpl implementation for the remote compositor. The lifetime of
+// this class is tied to the lifetime of the main components of the remote
+// compositor on the engine and the RemoteChannelHostClient.
+//
+// The object life cycle and communication across threads is as follows:
+//
+// The RemoteChannelImpl is created by the RemoteChannelHost on receiving
+// CompositorMessageToImpl:: InitializeImpl message from the main compositor.
+//
+//           Main Thread              |               Impl Thread
+//                                    |
+// RemoteChannelHost::                |
+//          CreateRemoteChannelImpl() |
+//               |                    |
+//               |              RemoteChannelImpl
+// ---------------------------------------------------------------------------
+// RemoteChannelImpl::Initialize()---PostTask---> RemoteChannelImpl::
+//                                                    InitializeImplOnImpl
+//                                                          |
+//                                                   ProxyImpl::Create
+//                                                          |
+//                                                          .
+//                                                          .
+//                                          ProxyImpl::ScheduledActionBegin
+//                                                     OutputSurfaceCreation
+//                                                          |
+//                                         ChannelImpl::RequestNewOutputSurface
+//                                                          |
+// RemoteChannelImpl::                                      |
+//      RequestNewOutputSurface()<----PostTask--------------
+//              .
+//              .
+//              |
+// RemoteChannelImpl::
+//          ~RemoteChannelImpl() ---PostTask---> RemoteChannelImpl::
+//                                                      ShutdownImplOnImpl
+// ----------------------------------------------------------------------------
+//
+// The destruction of the RemoteChannelImpl can be triggered by the
+// RemoteChannelHost in 2 cases:
+// 1) On receiving a CompositorMessageToImpl::CloseImpl message from the main
+// compositor.
+// 2) When the RemoteChannelHost is being destroyed, which will destroy the
+// RemoteChannelImpl.
+//
+// The class is created and destroyed on the main thread but can be safely
+// called from the main or impl thread. It is safe to call RemoteChannelImpl on
+// the impl thread since:
+// 1) The only impl threaded callers of RemoteChannelImpl is the
+// RemoteChannelImpl itself and ProxyImpl which is created and owned by the
+// RemoteChannelImpl.
+// 2) The RemoteChannelImpl blocks the main thread in its dtor to wait for the
+// impl-thread teardown to complete, which ensures that any tasks queued to call
+// it on the impl thread are run before it is destroyed on the main thread.
+
+class CC_EXPORT RemoteChannelImpl : public ChannelImpl {
+ public:
+  static scoped_ptr<RemoteChannelImpl> Create(
+      RemoteChannelHost* remote_channel_host,
+      TaskGraphRunner* task_graph_runner,
+      const LayerTreeSettings& settings,
+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner);
+
+  ~RemoteChannelImpl() override;
+
+  void Initialize();
+
+  void HandleProto(const proto::CompositorMessageToImpl& proto);
+
+  // Should be called on impl thread only.
+  ProxyImpl* GetProxyImplForTesting() const;
+
+ protected:
+  RemoteChannelImpl(
+      RemoteChannelHost* remote_channel_host,
+      TaskGraphRunner* task_graph_runner,
+      const LayerTreeSettings& settings,
+      scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+      scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner);
+
+  // virtual for testing.
+  virtual scoped_ptr<ProxyImpl> CreateProxyImpl(
+      ChannelImpl* channel_impl,
+      LayerTreeHost* layer_tree_host,
+      TaskRunnerProvider* task_runner_provider,
+      scoped_ptr<BeginFrameSource> external_begin_frame_source);
+
+  bool MainFrameWillHappenForTesting();
+
+ private:
+  struct MainThreadOnly {
+    RemoteChannelHost* remote_channel_host;
+
+    // For the remote mode, the data from the LayerTreeHost of the main
+    // compositor is deserialized to this LayerTreeHost which is used by
+    // ProxyImpl for the commit.
+    //
+    // Since the lifetime of this LayerTreeHost has to be tied to the lifetime
+    // of the main compositor, it is created and owned by the RemoteChannelImpl.
+    //
+    // It is *important* to note that the purpose of this LayerTreeHost is to
+    // run impl-threaded operations. The only method that can be called on it
+    // from the main thread is LayerTreeHost::FromProtobuf, used to add the
+    // commit data to this host.
+    scoped_ptr<LayerTreeHost> layer_tree_host;
+
+    MainThreadOnly(
+        RemoteChannelImpl* remote_channel_impl,
+        RemoteChannelHost* remote_channel_host,
+        TaskGraphRunner* task_graph_runner,
+        const LayerTreeSettings& settings,
+        scoped_refptr<base::SingleThreadTaskRunner> main_task_runner,
+        scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner);
+    ~MainThreadOnly();
+  };
+
+  struct CompositorThreadOnly {
+    scoped_ptr<ProxyImpl> proxy_impl;
+    scoped_ptr<base::WeakPtrFactory<ProxyImpl>> proxy_impl_weak_factory;
+
+    CompositorThreadOnly();
+    ~CompositorThreadOnly();
+  };
+
+  // Called on impl thread.
+  // ChannelImpl implementation
+  void DidCompleteSwapBuffers() override;
+  void SetRendererCapabilitiesMainCopy(
+      const RendererCapabilities& capabilities) override;
+  void BeginMainFrameNotExpectedSoon() override;
+  void DidCommitAndDrawFrame() override;
+  void SetAnimationEvents(scoped_ptr<AnimationEventsVector> queue) override;
+  void DidLoseOutputSurface() override;
+  void RequestNewOutputSurface() override;
+  void DidInitializeOutputSurface(
+      bool success,
+      const RendererCapabilities& capabilities) override;
+  void DidCompletePageScaleAnimation() override;
+  void PostFrameTimingEventsOnMain(
+      scoped_ptr<FrameTimingTracker::CompositeTimingSet> composite_events,
+      scoped_ptr<FrameTimingTracker::MainFrameTimingSet> main_frame_events)
+      override;
+  void BeginMainFrame(
+      scoped_ptr<BeginMainFrameAndCommitState> begin_main_frame_state) override;
+
+  void InitializeImplOnImpl(CompletionEvent* completion,
+                            LayerTreeHost* layer_tree_host);
+  void ShutdownImplOnImpl(CompletionEvent* completion);
+
+  // Called on main thread.
+  void MainThreadHasStoppedFlinging();
+
+  MainThreadOnly& main();
+  CompositorThreadOnly& impl();
+  const CompositorThreadOnly& impl() const;
+
+  base::SingleThreadTaskRunner* MainThreadTaskRunner() const;
+  base::SingleThreadTaskRunner* ImplThreadTaskRunner() const;
+
+  // use accessors instead of these variables directly
+  MainThreadOnly main_thread_vars_unsafe_;
+  CompositorThreadOnly compositor_thread_vars_unsafe_;
+
+  TaskRunnerProvider* task_runner_provider_;
+
+  base::WeakPtr<ProxyImpl> proxy_impl_weak_ptr_;
+
+  DISALLOW_COPY_AND_ASSIGN(RemoteChannelImpl);
+};
+
+}  // namespace cc
+
+#endif  // CC_TREES_REMOTE_CHANNEL_IMPL_H_