Disable sync for default apps

chrome/browser/extensions/extension_prefs.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_EXTENSIONS_EXTENSION_PREFS_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 411 matching lines @@
   // Clears incognito session-only content settings for all extensions.
   void ClearIncognitoSessionOnlyContentSettings();
 
   // Returns true if the extension was installed from the Chrome Web Store.
   bool IsFromWebStore(const std::string& extension_id) const;
 
   // Returns true if the extension was installed from an App generated from a
   // bookmark.
   bool IsFromBookmark(const std::string& extension_id) const;
 
+  // Returns true if the extension was installed as a default app.
+  bool WasInstalledByDefault(const std::string& extension_id) const;
+
   // Helper method to acquire the installation time of an extension.
   // Returns base::Time() if the installation time could not be parsed or
   // found.
   base::Time GetInstallTime(const std::string& extension_id) const;
 
   static void RegisterUserPrefs(PrefService* prefs);
 
   ContentSettingsStore* content_settings_store() {
     return content_settings_store_.get();
   }
@@ skipping 120 matching lines @@
   scoped_ptr<ExtensionSorting> extension_sorting_;
 
   scoped_refptr<ContentSettingsStore> content_settings_store_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionPrefs);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_PREFS_H_