Remove VIEW_TYPE_WEB_CONTENTS and make default view type INVALID.

content/browser/web_contents/web_contents_impl.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_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #define CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 690 matching lines @@
   // remember it.
   bool temporary_zoom_settings_;
 
   // The intrinsic size of the page.
   gfx::Size preferred_size_;
 
   // Content restrictions, used to disable print/copy etc based on content's
   // (full-page plugins for now only) permissions.
   int content_restrictions_;
 
-  // Our view type. Default is VIEW_TYPE_WEB_CONTENTS.
+  // Type of view this WebContents is displaying.
   content::ViewType view_type_;
 
   // Color chooser that was opened by this tab.
   content::ColorChooser* color_chooser_;
 
   DISALLOW_COPY_AND_ASSIGN(WebContentsImpl);
 };
 
 #endif  // CONTENT_BROWSER_WEB_CONTENTS_WEB_CONTENTS_IMPL_H_