Move MessagePort implementation from android_webview to content

content/common/app_web_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 "content/common/content_export.h"
 #include "ipc/ipc_message_macros.h"
 
+#undef IPC_MESSAGE_EXPORT
+#define IPC_MESSAGE_EXPORT CONTENT_EXPORT
 #define IPC_MESSAGE_START AwMessagePortMsgStart
 
 //-----------------------------------------------------------------------------
 // MessagePort messages
 // These are messages sent from the browser to the renderer process.
 
 // Normally the postmessages are exchanged between the renderers and the message
 // itself is opaque to the browser process. The format of the message is a
 // WebSerializesScriptValue.  A WebSerializedScriptValue is a blink structure
 // and can only be serialized/deserialized in renderer. Further, we could not
 // have Blink or V8 on the browser side due to their relience on static
 // variables.
 //
-// For posting messages from Java (Webview) to JS, we pass the browser/renderer
-// boundary an extra time and convert the messages to a type that browser can
-// use. Since WebView is single-process this is not terribly expensive, but
-// if we can do the conversion at the browser, then we can drop this code.
+// For posting messages from Java (Android apps) to JS, we pass the
+// browser/renderer boundary an extra time and convert the messages to a type
+// that browser can use. Within the current implementation specificications,
+// where we use the main frame on the browser side and it always stays within
+// the same process this is not expensive, but if we can do the conversion at
+// the browser, then we can drop this code.
 
-// Important Note about multi-process situation: Webview is single process so
-// such a conversion does not increase the risk due to untrusted renderers.
-// However, in a multi-process scenario, the renderer that does the conversion
-// can be different then the renderer that receives the message. There are
-// 2 possible solutions to deal with this:
+// Important Note about multi-process situation: In a multi-process scenario,
+// the renderer that does the conversion can be theoretically different then the
+// renderer that receives the message. Although in the current implementation
+// this doesn't become an issue, there are 2 possible solutions to deal with
+// this and make the overall system more robust to future changes:
 // 1. Do the conversion at the browser side by writing a new serializer
 // deserializer for WebSerializedScriptValue
 // 2. Do the conversion at the content layer, at the renderer at the time of
-// receiveing the message. This may need adding new flags to indicate that
+// receiving the message. This may need adding new flags to indicate that
 // message needs to be converted. However, this is complicated due to queing
 // at the browser side and possibility of ports being shipped to a different
 // renderer or browser delegate.
 
-
 // Tells the renderer to convert the message from a WebSerializeScript
 // format to a base::ListValue. This IPC is used for messages that are
-// incoming to Android webview from JS.
-IPC_MESSAGE_ROUTED3(AwMessagePortMsg_WebToAppMessage,
+// incoming to Android apps from JS.
+IPC_MESSAGE_ROUTED3(AppWebMessagePortMsg_WebToAppMessage,
                     int /* recipient message port id */,
                     base::string16 /* message */,
                     std::vector<int> /* sent message port_ids */)
 
 // Tells the renderer to convert the message from a String16
 // format to a WebSerializedScriptValue. This IPC is used for messages that
-// are outgoing from Webview to JS.
+// are outgoing from Android apps to JS.
 // TODO(sgurun) when we start supporting other types, use a ListValue instead
 // of string16
-IPC_MESSAGE_ROUTED3(AwMessagePortMsg_AppToWebMessage,
+IPC_MESSAGE_ROUTED3(AppWebMessagePortMsg_AppToWebMessage,
                     int /* recipient message port id */,
                     base::string16 /* message */,
                     std::vector<int> /* sent message port_ids */)
 
 // Used to defer message port closing until after all in-flight messages
 // are flushed from renderer to browser. Renderer piggy-backs the message
 // to browser.
-IPC_MESSAGE_ROUTED1(AwMessagePortMsg_ClosePort,
-                    int /* message port id */)
+IPC_MESSAGE_ROUTED1(AppWebMessagePortMsg_ClosePort, int /* message port id */)
 
 //-----------------------------------------------------------------------------
 // These are messages sent from the renderer to the browser process.
 
-// Response to AwMessagePortMessage_WebToAppMessage
-IPC_MESSAGE_ROUTED3(AwMessagePortHostMsg_ConvertedWebToAppMessage,
+// Response to AppWebMessagePortMessage_WebToAppMessage
+IPC_MESSAGE_ROUTED3(AppWebMessagePortHostMsg_ConvertedWebToAppMessage,
                     int /* recipient message port id */,
                     base::ListValue /* converted message */,
                     std::vector<int> /* sent message port_ids */)
 
-// Response to AwMessagePortMessage_AppToWebMessage
-IPC_MESSAGE_ROUTED3(AwMessagePortHostMsg_ConvertedAppToWebMessage,
+// Response to AppWebMessagePortMessage_AppToWebMessage
+IPC_MESSAGE_ROUTED3(AppWebMessagePortHostMsg_ConvertedAppToWebMessage,
                     int /* recipient message port id */,
                     base::string16 /* converted message */,
                     std::vector<int> /* sent message port_ids */)
 
-// Response to AwMessagePortMsg_ClosePort
-IPC_MESSAGE_ROUTED1(AwMessagePortHostMsg_ClosePortAck,
+// Response to AppWebMessagePortMsg_ClosePort
+IPC_MESSAGE_ROUTED1(AppWebMessagePortHostMsg_ClosePortAck,
                     int /* message port id */)