Move AppWindowContentsImpl to extensions

extensions/browser/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 
 # GYP version: extensions/extensions.gyp:extensions_browser
 source_set("browser") {
   sources = [
@@ skipping 148 matching lines @@
       "api/usb/usb_device_resource.h",
       "api/usb_private/usb_private_api.cc",
       "api/usb_private/usb_private_api.h",
       "api_activity_monitor.h",
       "app_sorting.h",
       "app_window/app_delegate.h",
       "app_window/app_web_contents_helper.cc",
       "app_window/app_web_contents_helper.h",
       "app_window/app_window.cc",
       "app_window/app_window.h",
+      "app_window/app_window_contents.cc",
+      "app_window/app_window_contents.h",
       "app_window/app_window_geometry_cache.cc",
       "app_window/app_window_geometry_cache.h",
       "app_window/app_window_registry.cc",
       "app_window/app_window_registry.h",
       "app_window/apps_client.cc",
       "app_window/apps_client.h",
       "app_window/native_app_window.h",
       "app_window/size_constraints.cc",
       "app_window/size_constraints.h",
       "blacklist_state.h",
@@ skipping 186 matching lines @@
       ]
     }
   }
 
   if (is_win) {
     cflags = [
       "/wd4267", # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     ]
   }
 }