Make URLDataSource::GetSource() const.

chrome/browser/ui/webui/fileicon_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_FILEICON_SOURCE_H_
 #define CHROME_BROWSER_UI_WEBUI_FILEICON_SOURCE_H_
 
 #include <string>
 
 #include "base/files/file_path.h"
 #include "chrome/browser/icon_manager.h"
 #include "chrome/common/cancelable_task_tracker.h"
 #include "content/public/browser/url_data_source.h"
 #include "ui/base/layout.h"
 
 namespace gfx {
 class Image;
 }
 
 // FileIconSource is the gateway between network-level chrome:
 // requests for favicons and the history backend that serves these.
 class FileIconSource : public content::URLDataSource {
  public:
   explicit FileIconSource();
 
   // content::URLDataSource implementation.
-  virtual std::string GetSource() OVERRIDE;
+  virtual std::string GetSource() const OVERRIDE;
   virtual void StartDataRequest(
       const std::string& path,
       bool is_incognito,
       const content::URLDataSource::GotDataCallback& callback) OVERRIDE;
   virtual std::string GetMimeType(const std::string&) const OVERRIDE;
 
  protected:
   virtual ~FileIconSource();
 
   // Once the |path| and |icon_size| has been determined from the request, this
@@ skipping 21 matching lines @@
   // Called when favicon data is available from the history backend.
   void OnFileIconDataAvailable(const IconRequestDetails& details,
                                gfx::Image* icon);
 
   // Tracks tasks requesting file icons.
   CancelableTaskTracker cancelable_task_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(FileIconSource);
 };
 #endif  // CHROME_BROWSER_UI_WEBUI_FILEICON_SOURCE_H_