Introduce lock screen app context to extension features

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 20 matching lines @@
   // The JavaScript contexts the feature is supported in.
   enum Context {
     UNSPECIFIED_CONTEXT,
     BLESSED_EXTENSION_CONTEXT,
     UNBLESSED_EXTENSION_CONTEXT,
     CONTENT_SCRIPT_CONTEXT,
     WEB_PAGE_CONTEXT,
     BLESSED_WEB_PAGE_CONTEXT,
     WEBUI_CONTEXT,
     SERVICE_WORKER_CONTEXT,
+    LOCK_SCREEN_EXTENSION_CONTEXT,
   };
 
   // The platforms the feature is supported in.
   enum Platform {
     UNSPECIFIED_PLATFORM,
     CHROMEOS_PLATFORM,
     LINUX_PLATFORM,
     MACOSX_PLATFORM,
     WIN_PLATFORM
   };
@@ skipping 102 matching lines @@
  protected:
   std::string name_;
   std::string alias_;
   std::string source_;
   bool no_parent_;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FEATURES_FEATURE_H_