Begin to enable extension APIs in Extension Service Worker.

extensions/common/extensions_client.h

 // Copyright 2013 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_COMMON_EXTENSIONS_CLIENT_H_
 #define EXTENSIONS_COMMON_EXTENSIONS_CLIENT_H_
 
 #include <memory>
 #include <set>
 #include <string>
@@ skipping 113 matching lines @@
   // extension unpacker to determine which assets should be transcoded safely
   // within the utility sandbox.
   //
   // The default implementation returns the images used as icons for the
   // extension itself, so implementors of ExtensionsClient overriding this may
   // want to call the base class version and then add additional paths to that
   // result.
   virtual std::set<base::FilePath> GetBrowserImagePaths(
       const Extension* extension);
 
+  // Returns whether or not extension APIs are allowed in extension service
+  // workers.
+  // This is currently disallowed as the code to support this is work in
+  // progress.
+  // Can be overridden in tests.
+  virtual bool ExtensionAPIEnabledInExtensionServiceWorkers() const;
+
   // Return the extensions client.
   static ExtensionsClient* Get();
 
   // Initialize the extensions system with this extensions client.
   static void Set(ExtensionsClient* client);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_EXTENSIONS_CLIENT_H_