Enable posting a message from JS to Android webview.

android_webview/common/aw_message_port_messages.h

+// Copyright 2015 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 file, no traditional include guard.
+#include <vector>
+
+#include "base/basictypes.h"
+#include "ipc/ipc_message_macros.h"
+
+#define IPC_MESSAGE_START AwMessagePortMsgStart
+
+//-----------------------------------------------------------------------------
+// MessagePort messages
+// These are messages sent from the browser to the renderer process.
+
+// Tells the renderer to convert the sent message from a WebSerializeScript
+// format to a base::ListValue. Due to the complexities of renderer/browser
+// relation, this can only be done in renderer for now.
+IPC_MESSAGE_ROUTED3(AwMessagePortMsg_Message,
+                    int /* recipient message port id */,
+                    base::string16 /* message */,
+                    std::vector<int> /* sent message port_ids */)
+
+//-----------------------------------------------------------------------------
+// These are messages sent from the renderer to the browser process.
+
+// Response to AwMessagePortMessage_ConvertMessage
+IPC_MESSAGE_ROUTED3(AwMessagePortHostMsg_ConvertedMessage,
+                    int /* recipient message port id */,
+                    base::ListValue /* converted message */,
+                    std::vector<int> /* sent message port_ids */)