Implement Device Orientation using shared memory in content/renderer.

content/common/device_orientation_messages.h

-// Copyright (c) 2012 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.
-
-// IPC messages for device orientation.
-// Multiply-included message file, hence no include guard.
-
-#include "ipc/ipc_message_macros.h"
-
-#define IPC_MESSAGE_START DeviceOrientationMsgStart
-
-IPC_STRUCT_BEGIN(DeviceOrientationMsg_Updated_Params)
-  // These fields have the same meaning as in content::Orientation.
-  IPC_STRUCT_MEMBER(bool, can_provide_alpha)
-  IPC_STRUCT_MEMBER(double, alpha)
-  IPC_STRUCT_MEMBER(bool, can_provide_beta)
-  IPC_STRUCT_MEMBER(double, beta)
-  IPC_STRUCT_MEMBER(bool, can_provide_gamma)
-  IPC_STRUCT_MEMBER(double, gamma)
-  IPC_STRUCT_MEMBER(bool, can_provide_absolute)
-  IPC_STRUCT_MEMBER(bool, absolute)
-IPC_STRUCT_END()
-
-// Messages sent from the browser to the renderer.
-
-// Notification that the device's orientation has changed.
-IPC_MESSAGE_ROUTED1(DeviceOrientationMsg_Updated,
-                    DeviceOrientationMsg_Updated_Params)
-
-// Messages sent from the renderer to the browser.
-
-// A RenderView requests to start receiving device orientation updates.
-IPC_MESSAGE_CONTROL1(DeviceOrientationHostMsg_StartUpdating,
-                     int /* render_view_id */)
-
-// A RenderView requests to stop receiving device orientation updates.
-IPC_MESSAGE_CONTROL1(DeviceOrientationHostMsg_StopUpdating,
-                     int /* render_view_id */)