[Extensions] Clean up the handling of ExtensionHostMsg_Request

extensions/browser/extension_web_contents_observer.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 EXTENSIONS_BROWSER_EXTENSION_WEB_CONTENTS_OBSERVER_H_
 #define EXTENSIONS_BROWSER_EXTENSION_WEB_CONTENTS_OBSERVER_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "content/public/browser/web_contents_observer.h"
+#include "extensions/browser/extension_function_dispatcher.h"
 
 namespace content {
 class BrowserContext;
 class RenderViewHost;
 class WebContents;
 }
 
 namespace extensions {
 class Extension;
 
 // A web contents observer used for renderer and extension processes. Grants the
 // renderer access to certain URL scheme patterns for extensions and notifies
 // the renderer that the extension was loaded.
 //
 // Extension system embedders must create an instance for every extension
 // WebContents. It must be a subclass so that creating an instance via
 // content::WebContentsUserData::CreateForWebContents() provides an object of
 // the correct type. For an example, see ChromeExtensionWebContentsObserver.
-class ExtensionWebContentsObserver : public content::WebContentsObserver {
+class ExtensionWebContentsObserver
+    : public content::WebContentsObserver,
+      public ExtensionFunctionDispatcher::Delegate {
+ public:
+  // Returns the ExtensionWebContentsObserver for the given |web_contents|.
+  static ExtensionWebContentsObserver* GetForWebContents(
+      content::WebContents* web_contents);
+
+  ExtensionFunctionDispatcher* dispatcher() { return &dispatcher_; }
+
  protected:
   explicit ExtensionWebContentsObserver(content::WebContents* web_contents);
   ~ExtensionWebContentsObserver() override;
 
   content::BrowserContext* browser_context() { return browser_context_; }
 
+  // ExtensionFunctionDispatcher::Delegate overrides.
+  content::WebContents* GetAssociatedWebContents() const override;
+
   // content::WebContentsObserver overrides.
 
   // A subclass should invoke this method to finish extension process setup.
   void RenderViewCreated(content::RenderViewHost* render_view_host) override;
 
   void RenderFrameCreated(content::RenderFrameHost* render_frame_host) override;
 
+  // Subclasses should call this first before doing their own message handling.
+  bool OnMessageReceived(const IPC::Message& message) override;
+
   // Per the documentation in WebContentsObserver, these two methods are
   // appropriate to track the set of current RenderFrameHosts.
   // NOTE: FrameDeleted() != RenderFrameDeleted().
   void FrameDeleted(content::RenderFrameHost* render_frame_host) override;
   void RenderFrameHostChanged(content::RenderFrameHost* old_host,
                               content::RenderFrameHost* new_host) override;
 
   // Per the documentation in WebContentsObserver, these two methods are invoked
   // when a Pepper plugin instance is attached/detached in the page DOM.
   void PepperInstanceCreated() override;
   void PepperInstanceDeleted() override;
 
   // Returns the extension or app associated with a render view host. Returns
   // NULL if the render view host is not for a valid extension.
   const Extension* GetExtension(content::RenderViewHost* render_view_host);
 
   // Updates ViewType for RenderViewHost based on GetViewType(web_contents()).
   void NotifyRenderViewType(content::RenderViewHost* render_view_host);
 
   // Returns the extension or app ID associated with a render view host. Returns
   // the empty string if the render view host is not for a valid extension.
   static std::string GetExtensionId(content::RenderViewHost* render_view_host);
 
  private:
+  void OnRequest(const ExtensionHostMsg_Request_Params& params);
+
   // The BrowserContext associated with the WebContents being observed.
   content::BrowserContext* browser_context_;
 
+  ExtensionFunctionDispatcher dispatcher_;
+
   DISALLOW_COPY_AND_ASSIGN(ExtensionWebContentsObserver);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_WEB_CONTENTS_OBSERVER_H_