cc/blimp: Add a LayerTreeHostRemote implementation.

cc/blimp/compositor_proto_state_sink_client.h

Index: cc/blimp/compositor_proto_state_sink_client.h
diff --git a/cc/blimp/compositor_proto_state_sink_client.h b/cc/blimp/compositor_proto_state_sink_client.h
new file mode 100644
index 0000000000000000000000000000000000000000..ecec8307fb2c497c03a899e765d13bd489f74e8a
--- /dev/null
+++ b/cc/blimp/compositor_proto_state_sink_client.h
@@ -0,0 +1,34 @@
+// 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_COMPOSITOR_PROTO_STATE_SINK_CLIENT_H_
+#define CC_BLIMP_COMPOSITOR_PROTO_STATE_SINK_CLIENT_H_
+
+#include "base/macros.h"
+#include "cc/base/cc_export.h"
+
+namespace base {
+class SingleThreadTaskRunner;
+}  // namespace base
+
+namespace cc {
+class CompositorProtoState;
+
+class CC_EXPORT CompositorProtoStateSinkClient {
+ public:
+  virtual ~CompositorProtoStateSinkClient() {}
+
+  // Called in response to a ScheduleMainFrame request made on the
+  // CompositorProtoStateSink.
+  // Note: The method should always be invoked asynchronously after the request
+  // is made.
+  virtual void BeginMainFrame() = 0;
+
+  // Returns the task runner for the compositor's main thread.
+  virtual base::SingleThreadTaskRunner* GetMainTaskRunner() = 0;

[danakj, 2016/09/26 21:36:52]

Why do you need this?

[Khushal, 2016/09/27 01:07:48]

My understanding was that the task runner that is given to the compositor for
the main thread is created using the renderer scheduler. I was initially using
ThreadTaskRunnerHandler::Get but that would be for the render thread's message
loop right?

[danakj, 2016/09/27 20:32:43]

If you passed in the task runner you already have it so why do you need to query
it from cc again? Can we just use the thing we passed to cc?

[Khushal, 2016/09/27 23:46:55]

Oh you mean like pass it to the CompositorProtoStateSink when its built? That
makes sense, we are going to go out to the ContentRendererClient from
RenderThreadImpl to make it so we can pass the task runner there. I'll add a
ctor for the CompositorProtoStateSink that takes a task runner instead. Does
that sound correct?

[Khushal, 2016/09/28 19:47:16]

Done.

+};
+
+}  // namespace cc
+
+#endif  // CC_BLIMP_COMPOSITOR_PROTO_STATE_SINK_CLIENT_H_