Makes mojo WebUI run main only after page finishes loading

content/renderer/web_ui_mojo.h

 // Copyright 2014 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 CONTENT_RENDERER_WEB_UI_MOJO_H_
 #define CONTENT_RENDERER_WEB_UI_MOJO_H_
 
 #include <string>
 
 #include "content/public/renderer/render_frame_observer.h"
@@ skipping 24 matching lines @@
 
  private:
   class MainFrameObserver : public RenderFrameObserver {
    public:
     explicit MainFrameObserver(WebUIMojo* web_ui_mojo);
     virtual ~MainFrameObserver();
 
     // RenderFrameObserver overrides:
     virtual void WillReleaseScriptContext(v8::Handle<v8::Context> context,
                                           int world_id) OVERRIDE;
+    virtual void DidFinishDocumentLoad() OVERRIDE;
 
    private:
     WebUIMojo* web_ui_mojo_;
 
     DISALLOW_COPY_AND_ASSIGN(MainFrameObserver);
   };
 
   virtual ~WebUIMojo();
 
   void CreateContextState();
   void DestroyContextState(v8::Handle<v8::Context> context);
 
+  // Invoked when the frame finishes loading. Invokes SetHandleOnContextState()
+  // if necessary.
+  void OnDidFinishDocumentLoad();
+
+  // Invokes SetHandle() on the WebUIMojoContextState (if there is one).
+  void SetHandleOnContextState(mojo::ScopedMessagePipeHandle handle);
+
   WebUIMojoContextState* GetContextState();
 
   // RenderViewObserver overrides:
   virtual void DidClearWindowObject(blink::WebFrame* frame,
                                     int world_id) OVERRIDE;
 
   MainFrameObserver main_frame_observer_;
 
+  // Set to true in DidFinishDocumentLoad(). 'main' is only executed once this
+  // happens.
+  bool did_finish_document_load_;
+
+  // If SetBrowserHandle() is invoked before the document finishes loading the
+  // MessagePipeHandle is stored here. When the document finishes loading
+  // SetHandleOnContextState() is invoked to send the handle to the
+  // WebUIMojoContextState and ultimately the page.
+  mojo::ScopedMessagePipeHandle pending_handle_;
+
   DISALLOW_COPY_AND_ASSIGN(WebUIMojo);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_WEB_UI_MOJO_H_