NTP: Prevent tab sync icons from being cached.

chrome/browser/ui/webui/chrome_url_data_manager.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_CHROME_URL_DATA_MANAGER_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROME_URL_DATA_MANAGER_H_
 #pragma once
 
 #include <string>
 #include <vector>
@@ skipping 89 matching lines @@
 
     // Returns true if this DataSource should replace an existing DataSource
     // with the same name that has already been registered. The default is
     // true.
     //
     // WARNING: this is invoked on the IO thread.
     //
     // TODO: nuke this and convert all callers to not replace.
     virtual bool ShouldReplaceExistingSource() const;
 
+    // Returns true if responses from this DataSource can be cached.
+    virtual bool AllowCaching() const { return true; }
+
     static void SetFontAndTextDirection(
         base::DictionaryValue* localized_strings);
 
    protected:
     virtual ~DataSource();
 
    private:
     friend class ChromeURLDataManagerBackend;
     friend class ChromeURLDataManager;
     friend class base::DeleteHelper<DataSource>;
@@ skipping 65 matching lines @@
   const base::Callback<ChromeURLDataManagerBackend*(void)> backend_;
 
   // |data_sources_| that are no longer referenced and scheduled for deletion.
   // Protected by g_delete_lock in the .cc file.
   static DataSources* data_sources_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeURLDataManager);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROME_URL_DATA_MANAGER_H_