Remove VIEW_TYPE_NOTIFICATION since it's not used anymore.

extensions/common/view_type.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 EXTENSIONS_COMMON_VIEW_TYPE_H_
 #define EXTENSIONS_COMMON_VIEW_TYPE_H_
 
 namespace extensions {
 
 // Icky RTTI used by a few systems to distinguish the host type of a given
 // WebContents.
 //
 // TODO(aa): Remove this and teach those systems to keep track of their own
 // data.
 enum ViewType {
   VIEW_TYPE_INVALID,
   VIEW_TYPE_APP_WINDOW,
   VIEW_TYPE_BACKGROUND_CONTENTS,
   VIEW_TYPE_EXTENSION_BACKGROUND_PAGE,
   VIEW_TYPE_EXTENSION_DIALOG,
   VIEW_TYPE_EXTENSION_INFOBAR,
   VIEW_TYPE_EXTENSION_POPUP,
-  // TODO(jam): remove this once http://crbug.com/137297 is fixed and HTML5
-  // notifications don't use WebContents.
-  VIEW_TYPE_NOTIFICATION,
   VIEW_TYPE_PANEL,
   VIEW_TYPE_TAB_CONTENTS,
   VIEW_TYPE_VIRTUAL_KEYBOARD,
   VIEW_TYPE_LAST = VIEW_TYPE_VIRTUAL_KEYBOARD
 };
 
 // Constant strings corresponding to the Type enumeration values.  Used
 // when converting JS arguments.
 extern const char kViewTypeAll[];
 extern const char kViewTypeAppWindow[];
 extern const char kViewTypeBackgroundPage[];
 extern const char kViewTypeExtensionDialog[];
 extern const char kViewTypeInfobar[];
-extern const char kViewTypeNotification[];
 extern const char kViewTypePanel[];
 extern const char kViewTypePopup[];
 extern const char kViewTypeTabContents[];
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_VIEW_TYPE_H_