Add extensions code to use common updater in components/update_client/

extensions/browser/extension_system.h

 // Copyright 2014 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 EXTENSIONS_BROWSER_EXTENSION_SYSTEM_H_
 #define EXTENSIONS_BROWSER_EXTENSION_SYSTEM_H_
 
 #include <string>
 
 #include "base/callback_forward.h"
@@ skipping 104 matching lines @@
   virtual const OneShotEvent& ready() const = 0;
 
   // Returns the content verifier, if any.
   virtual ContentVerifier* content_verifier() = 0;
 
   // Get a set of extensions that depend on the given extension.
   // TODO(elijahtaylor): Move SharedModuleService out of chrome/browser
   // so it can be retrieved from ExtensionSystem directly.
   virtual scoped_ptr<ExtensionSet> GetDependentExtensions(
       const Extension* extension) = 0;
+
+  // Install an updated version of |extension_id| with the version given in
+  // temp_dir. Ownership of |temp_dir| in the filesystem is transferred and
+  // implementors of this function are responsible for cleaning it up on
+  // errors, etc.
+  virtual void InstallUpdate(const std::string& extension_id,
+                             const base::FilePath& temp_dir) = 0;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_EXTENSION_SYSTEM_H_