Don't use browser windows for platform app shell windows

chrome/browser/ui/browser.h

 // Copyright (c) 2011 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 CHROME_BROWSER_UI_BROWSER_H_
 #define CHROME_BROWSER_UI_BROWSER_H_
 #pragma once
 
 #include <map>
 #include <set>
@@ skipping 80 matching lines @@
                 public InstantDelegate {
  public:
   // SessionService::WindowType mirrors these values.  If you add to this
   // enum, look at SessionService::WindowType to see if it needs to be
   // updated.
   enum Type {
     // If you add a new type, consider updating the test
     // BrowserTest.StartMaximized.
     TYPE_TABBED = 1,
     TYPE_POPUP = 2,
-    TYPE_PANEL = 3,
-    TYPE_SHELL = 4
+    TYPE_PANEL = 3
   };
 
   // Possible elements of the Browser window.
   enum WindowFeature {
     FEATURE_NONE = 0,
     FEATURE_TITLEBAR = 1,
     FEATURE_TABSTRIP = 2,
     FEATURE_TOOLBAR = 4,
     FEATURE_LOCATIONBAR = 8,
     FEATURE_BOOKMARKBAR = 16,
@@ skipping 739 matching lines @@
   void OnAcceptFullscreenPermission(const GURL& url,
                                     FullscreenExitBubbleType bubble_type);
   void OnDenyFullscreenPermission(FullscreenExitBubbleType bubble_type);
 
   // Figure out if there are tabs that have beforeunload handlers.
   bool TabsNeedBeforeUnloadFired();
 
   bool is_type_tabbed() const { return type_ == TYPE_TABBED; }
   bool is_type_popup() const { return type_ == TYPE_POPUP; }
   bool is_type_panel() const { return type_ == TYPE_PANEL; }
-  bool is_type_shell() const { return type_ == TYPE_SHELL; }
 
   bool is_app() const;
   bool is_devtools() const;
 
   // True when the current tab is in fullscreen mode, requested by
   // webkitRequestFullScreen.
   bool IsFullscreenForTab() const;
 
   // Called each time the browser window is shown.
   void OnWindowDidShow();
@@ skipping 556 matching lines @@
 
   scoped_refptr<FullscreenController> fullscreen_controller_;
 
   // True if the browser window has been shown at least once.
   bool window_has_shown_;
 
   DISALLOW_COPY_AND_ASSIGN(Browser);
 };
 
 #endif  // CHROME_BROWSER_UI_BROWSER_H_