Another attempt at fixing dead frames being tracked by webNavigation

chrome/browser/extensions/api/web_navigation/web_navigation_api.h

 // Copyright (c) 2012 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.
 
 // Defines the Chrome Extensions WebNavigation API functions for observing and
 // intercepting navigation events, as specified in the extension JSON API.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_WEB_NAVIGATION_WEB_NAVIGATION_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_WEB_NAVIGATION_WEB_NAVIGATION_API_H_
 
@@ skipping 95 matching lines @@
   void SendErrorEvents(content::WebContents* web_contents,
                        content::RenderViewHost* render_view_host,
                        FrameNavigationState::FrameID id_to_skip);
 
   // Tracks the state of the frames we are sending events for.
   FrameNavigationState navigation_state_;
 
   // Used for tracking registrations to redirect notifications.
   content::NotificationRegistrar registrar_;
 
+  // The current RenderViewHost of the observed WebContents.
   content::RenderViewHost* render_view_host_;
+
+  // During a cross site navigation, the WebContents has a second, pending
+  // RenderViewHost.
   content::RenderViewHost* pending_render_view_host_;
 
   DISALLOW_COPY_AND_ASSIGN(WebNavigationTabObserver);
 };
 
 // Observes navigation notifications and routes them as events to the extension
 // system.
 class WebNavigationEventRouter : public TabStripModelObserver,
                                  public chrome::BrowserListObserver,
                                  public content::NotificationObserver {
@@ skipping 74 matching lines @@
 // API function that returns the states of all frames in a given tab.
 class GetAllFramesFunction : public SyncExtensionFunction {
   virtual ~GetAllFramesFunction() {}
   virtual bool RunImpl() OVERRIDE;
   DECLARE_EXTENSION_FUNCTION_NAME("webNavigation.getAllFrames")
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_WEB_NAVIGATION_WEB_NAVIGATION_API_H_