Mark Render{Frame,View}::GetWebkitPreferences() return values as const.

content/public/renderer/render_view.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_PUBLIC_RENDERER_RENDER_VIEW_H_
 #define CONTENT_PUBLIC_RENDERER_RENDER_VIEW_H_
 
 #include <stddef.h>
 
 #include <string>
@@ skipping 53 matching lines @@
   // Get the routing ID of the view.
   virtual int GetRoutingID() const = 0;
 
   // Returns the size of the view.
   virtual gfx::Size GetSize() const = 0;
 
   // Returns the device scale factor of the display the render view is in.
   virtual float GetDeviceScaleFactor() const = 0;
 
   // Gets WebKit related preferences associated with this view.
-  virtual WebPreferences& GetWebkitPreferences() = 0;
+  virtual const WebPreferences& GetWebkitPreferences() = 0;
 
   // Overrides the WebKit related preferences associated with this view. Note
   // that the browser process may update the preferences at any time.
   virtual void SetWebkitPreferences(const WebPreferences& preferences) = 0;
 
   // Returns the associated WebView. May return NULL when the view is closing.
   virtual blink::WebView* GetWebView() = 0;
 
   // Returns the associated WebFrameWidget.
   virtual blink::WebFrameWidget* GetWebFrameWidget() = 0;
@@ skipping 45 matching lines @@
 
  private:
   // This interface should only be implemented inside content.
   friend class RenderViewImpl;
   RenderView() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_RENDERER_RENDER_VIEW_H_