Make PPAPI PostMessage behave asynchronously.

webkit/plugins/ppapi/message_channel.h

Index: webkit/plugins/ppapi/message_channel.h
===================================================================
--- webkit/plugins/ppapi/message_channel.h	(revision 79289)
+++ webkit/plugins/ppapi/message_channel.h	(working copy)
@@ -5,6 +5,7 @@
 #ifndef WEBKIT_PLUGINS_PPAPI_MESSAGE_CHANNEL_H_
 #define WEBKIT_PLUGINS_PPAPI_MESSAGE_CHANNEL_H_
 
+#include "base/task.h"
 #include "third_party/npapi/bindings/npruntime.h"
 #include "webkit/plugins/ppapi/resource.h"
 
@@ -44,7 +45,11 @@
   explicit MessageChannel(PluginInstance* instance);
   ~MessageChannel();
 
+  // Post a message to the onmessage handler for this channel's instance
+  // asynchronously.
   void PostMessageToJavaScript(PP_Var message_data);
+  // Post a message to the PPP_Instance HandleMessage function for this
+  // channel's instance.
   void PostMessageToNative(PP_Var message_data);
 
   // Return the NPObject* to which we should forward any calls which aren't
@@ -81,8 +86,22 @@
   // to a JavaScript target.
   NPVariant onmessage_invoker_;
 
+  // A function which evaluates the JavaScript code for onmessage_invoker_ and
+  // makes onmessage_invoker_ a callable NPVariant for that function.  Returns
+  // true on success, false otherwise.
   bool EvaluateOnMessageInvoker();
 
+  // Post a message to the onmessage handler for this channel's instance
+  // synchronously.  This is used by PostMessageToJavaScript.
+  void PostMessageToJavaScriptImpl(PP_Var message_data);
+  // Post a message to the PPP_Instance HandleMessage function for this
+  // channel's instance.  This is used by PostMessageToNative.
+  void PostMessageToNativeImpl(PP_Var message_data);
+
+  // Hold a ScopedRunnableMethodFactory so that when this MessageChannel is
+  // destroyed, any pending tasks (a.k.a. messages in the queue) will not fire.
+  ScopedRunnableMethodFactory<MessageChannel> method_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(MessageChannel);
 };