Speculative fix for crash in DOMUIThumbnailSource.

chrome/browser/dom_ui/dom_ui_favicon_source.h

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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_DOM_UI_DOM_UI_FAVICON_SOURCE_H_
 #define CHROME_BROWSER_DOM_UI_DOM_UI_FAVICON_SOURCE_H_
 #pragma once
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/scoped_ptr.h"
 #include "chrome/browser/dom_ui/chrome_url_data_manager.h"
 #include "chrome/browser/favicon_service.h"
 
 class GURL;
 class Profile;
 
 // FavIconSource is the gateway between network-level chrome:
 // requests for favicons and the history backend that serves these.
 class DOMUIFavIconSource : public ChromeURLDataManager::DataSource {
  public:
   explicit DOMUIFavIconSource(Profile* profile);
 
   // Called when the network layer has requested a resource underneath
   // the path we registered.
   virtual void StartDataRequest(const std::string& path,
                                 bool is_off_the_record,
                                 int request_id);
 
-  virtual std::string GetMimeType(const std::string&) const {
-    // We need to explicitly return a mime type, otherwise if the user tries to
-    // drag the image they get no extension.
-    return "image/png";
-  }
+  virtual std::string GetMimeType(const std::string&) const;
 
   // Called when favicon data is available from the history backend.
   void OnFavIconDataAvailable(FaviconService::Handle request_handle,
                               bool know_favicon,
                               scoped_refptr<RefCountedMemory> data,
                               bool expired,
                               GURL url);
 
  private:
-  virtual ~DOMUIFavIconSource() {}
+  virtual ~DOMUIFavIconSource();
 
   Profile* profile_;
   CancelableRequestConsumerT<int, 0> cancelable_consumer_;
 
   // Raw PNG representation of the favicon to show when the favicon
   // database doesn't have a favicon for a webpage.
   scoped_refptr<RefCountedMemory> default_favicon_;
 
   DISALLOW_COPY_AND_ASSIGN(DOMUIFavIconSource);
 };
 
 #endif  // CHROME_BROWSER_DOM_UI_DOM_UI_FAVICON_SOURCE_H_