Allow extension APIs to be called from WebUI.

extensions/common/features/feature.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_FEATURES_FEATURE_H_
 #define EXTENSIONS_COMMON_FEATURES_FEATURE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 26 matching lines @@
     // A context from a content script.
     CONTENT_SCRIPT_CONTEXT,
 
     // A normal web page. This should have an associated URL matching pattern.
     WEB_PAGE_CONTEXT,
 
     // A web page context which has been blessed by the user. Typically this
     // will be via the installation of a hosted app, so this may host an
     // extension. This is not affected by the URL matching pattern.
     BLESSED_WEB_PAGE_CONTEXT,
+
+    // A page within webui.
+    WEBUI_CONTEXT,
   };
 
   // The platforms the feature is supported in.
   enum Platform {
     UNSPECIFIED_PLATFORM,
     CHROMEOS_PLATFORM,
     LINUX_PLATFORM,
     MACOSX_PLATFORM,
     WIN_PLATFORM
   };
@@ skipping 96 matching lines @@
   virtual bool IsIdInWhitelist(const std::string& extension_id) const = 0;
 
  protected:
   std::string name_;
   bool no_parent_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_H_