Move GetNewTabCSS() caching off the startup path.

chrome/browser/ui/webui/theme_source.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_BROWSER_UI_WEBUI_THEME_SOURCE_H_
 #define CHROME_BROWSER_UI_WEBUI_THEME_SOURCE_H_
 
 #include <string>
 
 #include "base/compiler_specific.h"
@@ skipping 15 matching lines @@
   // content::URLDataSource implementation.
   std::string GetSource() const override;
   void StartDataRequest(
       const std::string& path,
       int render_process_id,
       int render_frame_id,
       const content::URLDataSource::GotDataCallback& callback) override;
   std::string GetMimeType(const std::string& path) const override;
   base::MessageLoop* MessageLoopForRequestPath(
       const std::string& path) const override;
-  bool ShouldReplaceExistingSource() const override;
   bool ShouldServiceRequest(const net::URLRequest* request) const override;
 
  private:
   // Fetches and sends the theme bitmap.
   void SendThemeBitmap(const content::URLDataSource::GotDataCallback& callback,
                        int resource_id,
                        float scale);
 
   // Used in place of SendThemeBitmap when the desired scale is larger than
   // what the resource bundle supports.  This can rescale the provided bitmap up
   // to the desired size.
   void SendThemeImage(const content::URLDataSource::GotDataCallback& callback,
                       int resource_id,
                       float scale);
 
-  // The original profile (never an OTR profile).
+  // The profile this object was initialized with.
   Profile* profile_;
 
-  // We grab the CSS early so we don't have to go back to the UI thread later.
-  scoped_refptr<base::RefCountedMemory> css_bytes_;
-
   DISALLOW_COPY_AND_ASSIGN(ThemeSource);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_THEME_SOURCE_H_