Remove VIEW_TYPE_WEB_CONTENTS and make default view type INVALID.

content/public/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 CONTENT_PUBLIC_COMMON_VIEW_TYPE_H_
 #define CONTENT_PUBLIC_COMMON_VIEW_TYPE_H_
 #pragma once
 
 namespace content {
 
-// Indicates different types of views.
+// Icky RTTI used by a few systems to distinguish the host type of a given
+// RenderViewHost or WebContents.
+//
+// TODO(aa): Remove this and teach those systems to keep track of their own
+// data.
 enum ViewTypeValues {
   VIEW_TYPE_INVALID,
-  VIEW_TYPE_WEB_CONTENTS,
   VIEW_TYPE_INTERSTITIAL_PAGE,
   VIEW_TYPE_DEV_TOOLS_UI,
-
   VIEW_TYPE_CONTENT_END
 };
 
 typedef int ViewType;
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_COMMON_VIEW_TYPE_H_