cc/blimp: Add a LayerTreeHostRemote implementation.

cc/blimp/remote_compositor_bridge.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_REMOTE_COMPOSITOR_BRIDGE_H_
+#define CC_BLIMP_REMOTE_COMPOSITOR_BRIDGE_H_
+
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "cc/base/cc_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace cc {
+class CompositorProtoState;
+class RemoteCompositorBridgeClient;
+
+// The RemoteCompositorBridge is the remote LTH's communication bridge to the
+// compositor on the client that consumes the CompositorProtoState updates and
+// performs the actual compositing work. It is responsible for scheduling
+// when a state update should be sent to the client and providing back
+// mutations made to the state on the client.
+class CC_EXPORT RemoteCompositorBridge {
+ public:
+  RemoteCompositorBridge(
+      scoped_refptr<base::SingleThreadTaskRunner> compositor_main_task_runner);
+
+  virtual ~RemoteCompositorBridge();
+
+  // Must be called exactly once before the RemoteCompositorBridge can be
+  // used. Once bound, the client is expected to outlive this class.
+  virtual void BindToClient(RemoteCompositorBridgeClient* client) = 0;
+
+  // Notifies the bridge that a main frame update is required.
+  virtual void ScheduleMainFrame() = 0;
+
+  // If a main frame update results in any mutations to the compositor state,
+  // the serialized compositor state is provided to the
+  // RemoteCompositorBridge.
+  virtual void ProcessCompositorStateUpdate(
+      std::unique_ptr<CompositorProtoState> compositor_proto_state) = 0;
+
+ protected:
+  // The task runner for the compositor's main thread. The
+  // RemoteCompositorBridgeClient must be called on this task runner.
+  scoped_refptr<base::SingleThreadTaskRunner> compositor_main_task_runner_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RemoteCompositorBridge);
+};
+
+}  // namespace cc
+#endif  // CC_BLIMP_REMOTE_COMPOSITOR_BRIDGE_H_