Add gamepad IPC message definitions, not in-use yet.

content/common/gamepad_messages.h

+// Copyright (c) 2011 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.
+
+// Multiply-included message file, no include guard.
+
+#include "ipc/ipc_message_macros.h"
+#include "ipc/ipc_param_traits.h"
+#include "ipc/ipc_platform_file.h"
+#include "base/shared_memory.h"
+
+#define IPC_MESSAGE_START GamepadMsgStart
+
+// Messages sent from the renderer to the browser.
+
+// Asks the browser process to start polling, and return a shared memory
+// handles that will hold the (triple-buffered) data from the hardware.
+// The number of Starts should match the number of Stops (below).
+IPC_SYNC_MESSAGE_CONTROL0_1(GamepadHostMsg_StartPolling,
+                            base::SharedMemoryHandle /* handle */)
+
+IPC_SYNC_MESSAGE_CONTROL0_0(GamepadHostMsg_StopPolling)
+
+
+// Messages sent from browser to renderer.
+
+IPC_MESSAGE_CONTROL1(GamepadMsg_Updated,
+                     int /* read_buffer_index */)