ozone: gpu: Add plumbing for platform-specific gpu messaging

ui/ozone/gpu/gpu_platform_support.h

+// Copyright 2014 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 UI_OZONE_GPU_GPU_PLATFORM_SUPPORT_H_
+#define UI_OZONE_GPU_GPU_PLATFORM_SUPPORT_H_
+
+#include "ipc/ipc_listener.h"
+#include "ipc/ipc_sender.h"
+#include "ui/ozone/gpu/ozone_gpu_export.h"
+
+namespace ui {
+
+// Conduit for display-related messaging from browser to GPU (gpu end).
+//
+// See GpuPlatformSupportHost for more context.
+class OZONE_GPU_EXPORT GpuPlatformSupport : public IPC::Listener {
+ public:
+  virtual ~GpuPlatformSupport() {}
+
+  // Initialize the static instance.
+  static GpuPlatformSupport* Initialize();

[alexst (slow to review), 2014/06/16 21:34:23]

Init returns the object here, so does GetInstance but GetInstance isn't called
anywhere that I can see. 
We also call ChannelEstablished right after Initialize. Same as my other
comment, should the platform init the object and OnChannelEstablished act as an
activation trigger?

+
+  // Get the static instance.
+  static GpuPlatformSupport* GetInstance();
+
+  // Called when the GPU process is spun up & channel established.
+  virtual void OnChannelEstablished(IPC::Sender* sender, int route_id) = 0;
+
+ private:
+  static GpuPlatformSupport* instance_;
+};
+
+// Create a stub implementation.
+OZONE_GPU_EXPORT GpuPlatformSupport* CreateStubGpuPlatformSupport();
+
+}  // namespace ui
+
+#endif  // UI_OZONE_GPU_GPU_PLATFORM_SUPPORT_H_