Prevent derived classes of GuestViewBase from overriding key methods

chrome/browser/guest_view/guest_view_base.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 CHROME_BROWSER_GUEST_VIEW_GUEST_VIEW_BASE_H_
 #define CHROME_BROWSER_GUEST_VIEW_GUEST_VIEW_BASE_H_
 
 #include <queue>
 
 #include "base/memory/weak_ptr.h"
@@ skipping 58 matching lines @@
                                              std::string* partition_domain,
                                              std::string* partition_name,
                                              bool* in_memory);
 
   // By default, JavaScript and images are enabled in guest content.
   static void GetDefaultContentSettingRules(RendererContentSettingRules* rules,
                                             bool incognito);
 
   virtual const char* GetViewType() const = 0;
 
-  // This method can be overriden by subclasses. This method is called when
+  // This method can be overridden by subclasses. This method is called when
   // the initial set of frames within the page have completed loading.
   virtual void DidStopLoading() {}
 
-  // This method can be overridden by subclasses. It indicates that this guest's
-  // embedder has been destroyed and the guest will be destroyed shortly. This
-  // method gives derived classes the opportunity to perform some cleanup.
+  // This method is called when the guest WebContents is about to be destroyed.
+  //
+  // This method can be overridden by subclasses. This gives the derived class
+  // an opportunity to perform some cleanup prior to destruction.
+  virtual void WillDestroy() {}
+
+  // This method is called when the guest's embedder WebContents has been
+  // destroyed and the guest will be destroyed shortly.
+  //
+  // This method can be overridden by subclasses. This gives the derived class
+  // an opportunity to perform some cleanup prior to destruction.
   virtual void EmbedderDestroyed() {}
 
+  // This method is called when the guest WebContents has been destroyed. This
+  // object will be destroyed after this call returns.
+  //
+  // This method can be overridden by subclasses. This gives the derived class
+  // opportunity to perform some cleanup.
+  virtual void GuestDestroyed() {}
+
   // This method queries whether drag-and-drop is enabled for this particular
   // view. By default, drag-and-drop is disabled. Derived classes can override
   // this behavior to enable drag-and-drop.
   virtual bool IsDragAndDropEnabled() const;
 
   bool IsViewType(const char* const view_type) const {
     return !strcmp(GetViewType(), view_type);
   }
 
   base::WeakPtr<GuestViewBase> AsWeakPtr();
@@ skipping 38 matching lines @@
 
   // Returns the embedder's process ID.
   int embedder_render_process_id() const { return embedder_render_process_id_; }
 
   GuestViewBase* GetOpener() const {
     return opener_.get();
   }
 
   void SetOpener(GuestViewBase* opener);
 
-  // WebContentsObserver implementation.
-  virtual void DidStopLoading(
-      content::RenderViewHost* render_view_host) OVERRIDE FINAL;
-  virtual void WebContentsDestroyed() OVERRIDE;
+  // BrowserPluginGuestDelegate implementation.
+  virtual void Destroy() OVERRIDE FINAL;
+  virtual void RegisterDestructionCallback(
+      const DestructionCallback& callback) OVERRIDE FINAL;
 
-  // WebContentsDelegate implementation.
-  virtual bool ShouldFocusPageAfterCrash() OVERRIDE;
-  virtual bool PreHandleGestureEvent(
-      content::WebContents* source,
-      const blink::WebGestureEvent& event) OVERRIDE;
-
-  // BrowserPluginGuestDelegate implementation.
-  virtual void Destroy() OVERRIDE;
-  virtual void RegisterDestructionCallback(
-      const DestructionCallback& callback) OVERRIDE;
  protected:
   GuestViewBase(int guest_instance_id,
                 content::WebContents* guest_web_contents,
                 const std::string& embedder_extension_id);
   virtual ~GuestViewBase();
 
   // Dispatches an event |event_name| to the embedder with the |event| fields.
   void DispatchEvent(Event* event);
 
  private:
   class EmbedderWebContentsObserver;
 
   void SendQueuedEvents();
 
+  // WebContentsObserver implementation.
+  virtual void DidStopLoading(
+      content::RenderViewHost* render_view_host) OVERRIDE FINAL;
+  virtual void WebContentsDestroyed() OVERRIDE FINAL;
+
+  // WebContentsDelegate implementation.
+  virtual bool ShouldFocusPageAfterCrash() OVERRIDE FINAL;
+  virtual bool PreHandleGestureEvent(
+      content::WebContents* source,
+      const blink::WebGestureEvent& event) OVERRIDE FINAL;
+
   content::WebContents* embedder_web_contents_;
   const std::string embedder_extension_id_;
   int embedder_render_process_id_;
   content::BrowserContext* const browser_context_;
   // |guest_instance_id_| is a profile-wide unique identifier for a guest
   // WebContents.
   const int guest_instance_id_;
   // |view_instance_id_| is an identifier that's unique within a particular
   // embedder RenderViewHost for a particular <*view> instance.
   int view_instance_id_;
@@ skipping 16 matching lines @@
   scoped_ptr<EmbedderWebContentsObserver> embedder_web_contents_observer_;
 
   // This is used to ensure pending tasks will not fire after this object is
   // destroyed.
   base::WeakPtrFactory<GuestViewBase> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GuestViewBase);
 };
 
 #endif  // CHROME_BROWSER_GUEST_VIEW_GUEST_VIEW_BASE_H_