Cache the current WebPreferences on RenderViewHostImpl (try #2).

content/browser/web_contents/web_contents_impl.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.
 
 #ifndef CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 399 matching lines @@
   virtual void RouteCloseEvent(RenderViewHost* rvh) OVERRIDE;
   virtual void RouteMessageEvent(
       RenderViewHost* rvh,
       const ViewMsg_PostMessage_Params& params) OVERRIDE;
   virtual bool AddMessageToConsole(int32 level,
                                    const base::string16& message,
                                    int32 line_no,
                                    const base::string16& source_id) OVERRIDE;
   virtual RendererPreferences GetRendererPrefs(
       BrowserContext* browser_context) const OVERRIDE;
-  virtual WebPreferences GetWebkitPrefs() OVERRIDE;
+  virtual WebPreferences ComputeWebkitPrefs() OVERRIDE;
   virtual void OnUserGesture() OVERRIDE;
   virtual void OnIgnoredUIEvent() OVERRIDE;
   virtual void RendererUnresponsive(RenderViewHost* render_view_host,
                                     bool is_during_beforeunload,
                                     bool is_during_unload) OVERRIDE;
   virtual void RendererResponsive(RenderViewHost* render_view_host) OVERRIDE;
   virtual void LoadStateChanged(const GURL& url,
                                 const net::LoadStateWithParam& load_state,
                                 uint64 upload_position,
                                 uint64 upload_size) OVERRIDE;
@@ skipping 763 matching lines @@
   // The accessibility mode for all frames. This is queried when each frame
   // is created, and broadcast to all frames when it changes.
   AccessibilityMode accessibility_mode_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_