Move the Extension Port implementation out of messaging.js into its own file port.js.

extensions/renderer/resources/messaging.js

Index: extensions/renderer/resources/messaging.js
diff --git a/extensions/renderer/resources/messaging.js b/extensions/renderer/resources/messaging.js
index 7a5c91040305c2ea9a86acc6020276f5b278bc29..9fc29d49752b1e788edc7015cf1c8e4725e5f5e6 100644
--- a/extensions/renderer/resources/messaging.js
+++ b/extensions/renderer/resources/messaging.js
@@ -6,14 +6,13 @@
 
   // TODO(kalman): factor requiring chrome out of here.
   var chrome = requireNative('chrome').GetChrome();
-  var Event = require('event_bindings').Event;
   var lastError = require('lastError');
   var logActivity = requireNative('activityLogger');
   var logging = requireNative('logging');
   var messagingNatives = requireNative('messaging_natives');
+  var Port = require('port').Port;
   var processNatives = requireNative('process');
   var unloadEvent = require('unload_event');
-  var utils = require('utils');
   var messagingUtils = require('messaging_utils');
 
   // The reserved channel name for the sendRequest/send(Native)Message APIs.
@@ -33,64 +32,6 @@
   // channel.
   function getOppositePortId(portId) { return portId ^ 1; }
 
-  // Port object.  Represents a connection to another script context through
-  // which messages can be passed.
-  function PortImpl(portId, opt_name) {
-    this.portId_ = portId;
-    this.name = opt_name;
-
-    var portSchema = {name: 'port', $ref: 'runtime.Port'};
-    var options = {unmanaged: true};
-    this.onDisconnect = new Event(null, [portSchema], options);
-    this.onMessage = new Event(
-        null,
-        [{name: 'message', type: 'any', optional: true}, portSchema],
-        options);
-    this.onDestroy_ = null;
-  }
-
-  // Sends a message asynchronously to the context on the other end of this
-  // port.
-  PortImpl.prototype.postMessage = function(msg) {
-    // JSON.stringify doesn't support a root object which is undefined.
-    if (msg === undefined)
-      msg = null;
-    msg = $JSON.stringify(msg);
-    if (msg === undefined) {
-      // JSON.stringify can fail with unserializable objects. Log an error and
-      // drop the message.
-      //
-      // TODO(kalman/mpcomplete): it would be better to do the same validation
-      // here that we do for runtime.sendMessage (and variants), i.e. throw an
-      // schema validation Error, but just maintain the old behaviour until
-      // there's a good reason not to (http://crbug.com/263077).
-      console.error('Illegal argument to Port.postMessage');
-      return;
-    }
-    messagingNatives.PostMessage(this.portId_, msg);
-  };
-
-  // Disconnects the port from the other end.
-  PortImpl.prototype.disconnect = function() {
-    messagingNatives.CloseChannel(this.portId_, true);
-    this.destroy_();
-  };
-
-  PortImpl.prototype.destroy_ = function() {
-    var portId = this.portId_;
-
-    if (this.onDestroy_)
-      this.onDestroy_();
-    privates(this.onDisconnect).impl.destroy_();
-    privates(this.onMessage).impl.destroy_();
-
-    messagingNatives.PortRelease(portId);
-    unloadEvent.removeListener(portReleasers[portId]);
-
-    delete ports[portId];
-    delete portReleasers[portId];
-  };
-
   // Returns true if the specified port id is in this context. This is used by
   // the C++ to avoid creating the javascript message for all the contexts that
   // don't care about a particular message.
@@ -113,6 +54,14 @@
     return port;
   };
 
+  // Called when a Port is destroyed. Does general accounting cleanup.
+  function onPortDestroyed(port) {
+    var portId = privates(port).impl.portId_;
+    unloadEvent.removeListener(portReleasers[portId]);
+    delete ports[portId];
+    delete portReleasers[portId];
+  }
+
   // Helper function for dispatchOnRequest.
   function handleSendRequestError(isSendMessage,
                                   responseCallbackPreserved,
@@ -200,6 +149,7 @@
 
     privates(port).impl.onDestroy_ = function() {
       port.onMessage.removeListener(messageListener);
+      onPortDestroyed(port);
     };
     port.onMessage.addListener(messageListener);
 
@@ -358,6 +308,7 @@
     privates(port).impl.onDestroy_ = function() {

[Devlin, 2015/04/17 00:14:52]

I don't love this part, especially now that it's in its own file.  How opposed
would you be to making a generic port.onDestroyedListener, that can be called
from port itself?

[not at google - send to devlin, 2015/04/17 00:16:34]

You need to be careful, because Ports are exposed directly to extensions and we
don't want to give those an onDestroyedListener.

When I create port manager this should go away.

[Devlin, 2015/04/17 00:25:52]

Right, in my mind there's:
Private private: Nothing but the class itself
Public private: Accessible through privates()
Public public: Accessible via extensions

Right now, this strikes me as the first - I was suggesting make it the second.

[not at google - send to devlin, 2015/04/17 00:27:59]

Heh, a distinction unique to these JS bindings.

Another design I had considered was to make some kind of InternalPort class
which handled the real Port to give to the extension. However, such an
InternalPort would belong inside the port manager, so if that's the design that
makes the most sense - that's what it will end up as.

       port.onDisconnect.removeListener(disconnectListener);
       port.onMessage.removeListener(messageListener);
+      onPortDestroyed(port);
     };
     port.onDisconnect.addListener(disconnectListener);
     port.onMessage.addListener(messageListener);
@@ -373,20 +324,9 @@
     return alignedArgs;
   }
 
-var Port = utils.expose('Port', PortImpl, { functions: [
-    'disconnect',
-    'postMessage'
-  ],
-  properties: [
-    'name',
-    'onDisconnect',
-    'onMessage'
-  ] });
-
 exports.kRequestChannel = kRequestChannel;
 exports.kMessageChannel = kMessageChannel;
 exports.kNativeMessageChannel = kNativeMessageChannel;
-exports.Port = Port;
 exports.createPort = createPort;
 exports.sendMessageImpl = sendMessageImpl;
 exports.sendMessageUpdateArguments = sendMessageUpdateArguments;