Remove chrome.windows.* support for platform apps.

chrome/common/extensions/api/windows.json

 // 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.
 
 [
   {
     "namespace": "windows",
     "dependencies": [ "tabs" ],
     "types": [
       {
         "id": "Window",
         "type": "object",
         "properties": {
           "id": {"type": "integer", "minimum": 0, "description": "The ID of the window. Window IDs are unique within a browser session."},
           "focused": {"type": "boolean", "description": "Whether the window is currently the focused window."},
           "top": {"type": "integer", "description": "The offset of the window from the top edge of the screen in pixels."},
           "left": {"type": "integer", "description": "The offset of the window from the left edge of the screen in pixels."},
           "width": {"type": "integer", "description": "The width of the window in pixels."},
           "height": {"type": "integer", "description": "The height of the window in pixels."},
           "tabs": {"type": "array", "items": { "$ref": "tabs.Tab" }, "optional": true, "description": "Array of $ref:tabs.Tab objects representing the current tabs in the window."},
           "incognito": {"type": "boolean", "description": "Whether the window is incognito."},
           "type": {
             "type": "string",
             "description": "The type of browser window this is.",
-            "enum": ["normal", "popup", "panel", "app", "shell"]
+            "enum": ["normal", "popup", "panel", "app"]
           },
           "state": {
             "type": "string",
             "description": "The state of this browser window.",
             "enum": ["normal", "minimized", "maximized", "fullscreen"]
           },
           "alwaysOnTop": {"type": "boolean", "description": "Whether the window is set to be always on top."}
         }
       }
     ],
@@ skipping 131 matching lines @@
               "left": {"type": "integer", "optional": true, "description": "The number of pixels to position the new window from the left edge of the screen. If not specified, the new window is offset naturally from the last focused window. This value is ignored for panels."},
               "top": {"type": "integer", "optional": true, "description": "The number of pixels to position the new window from the top edge of the screen. If not specified, the new window is offset naturally from the last focused window. This value is ignored for panels."},
               "width": {"type": "integer", "minimum": 0, "optional": true, "description": "The width in pixels of the new window. If not specified defaults to a natural width."},
               "height": {"type": "integer", "minimum": 0, "optional": true, "description": "The height in pixels of the new window. If not specified defaults to a natural height."},
               "focused": {"type": "boolean", "optional": true, "description": "If true, opens an active window. If false, opens an inactive window."},
               "incognito": {"type": "boolean", "optional": true, "description": "Whether the new window should be an incognito window."},
               "type": {
                 "type": "string",
                 "optional": true,
                 "description": "Specifies what type of browser window to create. The 'panel' type creates a popup unless the '--enable-panels' flag is set.",
-                "enum": ["normal", "popup", "panel", "shell"]
+                "enum": ["normal", "popup", "panel"]
               }
             },
             "optional": true
           },
           {
             "type": "function",
             "name": "callback",
             "optional": true,
             "parameters": [
               {
@@ skipping 75 matching lines @@
         "name": "onFocusChanged",
         "type": "function",
         "description": "Fired when the currently focused window changes. Will be chrome.windows.WINDOW_ID_NONE if all chrome windows have lost focus. Note: On some Linux window managers, WINDOW_ID_NONE will always be sent immediately preceding a switch from one chrome window to another.",
         "parameters": [
           {"type": "integer", "name": "windowId", "minimum": -1, "description": "ID of the newly focused window."}
         ]
       }
     ]
   }
 ]