Connects PostMessage() for OOPIFs

mandoline/tab/frame_tree_delegate.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.
 
 #ifndef MANDOLINE_TAB_FRAME_TREE_DELEGATE_H_
 #define MANDOLINE_TAB_FRAME_TREE_DELEGATE_H_
 
 #include "mandoline/tab/public/interfaces/frame_tree.mojom.h"
 #include "mojo/services/network/public/interfaces/url_loader.mojom.h"
 
 namespace mandoline {
 
 class Frame;
-class MessageEvent;
+class HTMLMessageEvent;
 
 class FrameTreeDelegate {
  public:
+  // Returns whether a request to post a message from |source| to |target|
+  // is allowed. |source| and |target| are never null.
   virtual bool CanPostMessageEventToFrame(const Frame* source,
                                           const Frame* target,
-                                          MessageEvent* event) = 0;
+                                          HTMLMessageEvent* event) = 0;
+
   virtual void LoadingStateChanged(bool loading) = 0;
   virtual void ProgressChanged(double progress) = 0;
 
   // |source| is requesting a navigation. If |target_type| is
   // |EXISTING_FRAME| then |target_frame| identifies the frame to perform the
   // navigation in, otherwise |target_frame| is not used. |target_frame| may
   // be null, even for |EXISTING_FRAME|.
   virtual void RequestNavigate(Frame* source,
                                NavigationTargetType target_type,
                                Frame* target_frame,
                                mojo::URLRequestPtr request) = 0;
 
  protected:
   virtual ~FrameTreeDelegate() {}
 };
 
 }  // namespace mandoline
 
 #endif  // MANDOLINE_TAB_FRAME_TREE_DELEGATE_H_