Allow transitions to WebUI pages which are extension urls (new tab page is the relevant example).

chrome/renderer/extensions/extension_resource_request_policy.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 CHROME_RENDERER_EXTENSIONS_EXTENSION_RESOURCE_REQUEST_POLICY_H_
 #define CHROME_RENDERER_EXTENSIONS_EXTENSION_RESOURCE_REQUEST_POLICY_H_
 
+#include "content/public/common/page_transition_types.h"
+
 class ExtensionSet;
 class GURL;
 namespace WebKit {
 class WebFrame;
 }
 
 // Encapsulates the policy for when chrome-extension:// and
 // chrome-extension-resource:// URLs can be requested.
 class ExtensionResourceRequestPolicy {
  public:
   // Returns true if the chrome-extension:// |resource_url| can be requested
-  // from |frame_url|.
+  // from |frame_url|. In some cases this decision is made based upon how
+  // this request was generated. Web triggered transitions are more restrictive
+  // than those triggered through UI.
   static bool CanRequestResource(const GURL& resource_url,
                                  WebKit::WebFrame* frame,
+                                 content::PageTransition transition_type,
                                  const ExtensionSet* loaded_extensions);
   // Returns true if the chrome-extension-resource:// |resource_url| can be
   // requested from |frame_url|.
   static bool CanRequestExtensionResourceScheme(
       const GURL& resource_url,
       WebKit::WebFrame* frame);
 
  private:
   ExtensionResourceRequestPolicy();
 };
 
 #endif  // CHROME_RENDERER_EXTENSIONS_EXTENSION_RESOURCE_REQUEST_POLICY_H_