Fix crash when user closes window prior to the "Confirm Install" prompt showing

chrome/chrome_browser_ui.gypi

 # Copyright 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.
 
 {
   'variables': {
     'chrome_browser_ui_non_ios_sources': [
       'browser/ui/accelerator_utils.h',
       'browser/ui/android/android_about_app_info.cc',
       'browser/ui/android/android_about_app_info.h',
@@ skipping 560 matching lines @@
       'browser/ui/cocoa/media_picker/desktop_media_picker_cocoa.h',
       'browser/ui/cocoa/media_picker/desktop_media_picker_cocoa.mm',
       'browser/ui/cocoa/media_picker/desktop_media_picker_controller.h',
       'browser/ui/cocoa/media_picker/desktop_media_picker_controller.mm',
       'browser/ui/cocoa/media_picker/desktop_media_picker_item.h',
       'browser/ui/cocoa/media_picker/desktop_media_picker_item.mm',
       'browser/ui/cocoa/menu_button.h',
       'browser/ui/cocoa/menu_button.mm',
       'browser/ui/cocoa/multi_key_equivalent_button.h',
       'browser/ui/cocoa/multi_key_equivalent_button.mm',
+      'browser/ui/cocoa/native_window_tracker_cocoa.h',
+      'browser/ui/cocoa/native_window_tracker_cocoa.mm',
       'browser/ui/cocoa/new_tab_button.h',
       'browser/ui/cocoa/new_tab_button.mm',
       'browser/ui/cocoa/notifications/message_center_tray_bridge.h',
       'browser/ui/cocoa/notifications/message_center_tray_bridge.mm',
       'browser/ui/cocoa/nsmenuitem_additions.h',
       'browser/ui/cocoa/nsmenuitem_additions.mm',
       'browser/ui/cocoa/omnibox/omnibox_popup_cell.h',
       'browser/ui/cocoa/omnibox/omnibox_popup_cell.mm',
       'browser/ui/cocoa/omnibox/omnibox_popup_matrix.h',
       'browser/ui/cocoa/omnibox/omnibox_popup_matrix.mm',
@@ skipping 833 matching lines @@
       'browser/ui/fullscreen/fullscreen_exit_bubble_type.cc',
       'browser/ui/fullscreen/fullscreen_exit_bubble_type.h',
       'browser/ui/fullscreen/fullscreen_within_tab_helper.cc',
       'browser/ui/fullscreen/fullscreen_within_tab_helper.h',
       'browser/ui/location_bar/location_bar.cc',
       'browser/ui/location_bar/location_bar.h',
       'browser/ui/location_bar/location_bar_util.cc',
       'browser/ui/location_bar/location_bar_util.h',
       'browser/ui/location_bar/origin_chip_info.cc',
       'browser/ui/location_bar/origin_chip_info.h',
+      'browser/ui/native_window_tracker.h',
       'browser/ui/omnibox/alternate_nav_infobar_delegate.cc',
       'browser/ui/omnibox/alternate_nav_infobar_delegate.h',
       'browser/ui/omnibox/omnibox_controller.cc',
       'browser/ui/omnibox/omnibox_controller.h',
       'browser/ui/omnibox/omnibox_current_page_delegate.h',
       'browser/ui/omnibox/omnibox_current_page_delegate_impl.cc',
       'browser/ui/omnibox/omnibox_current_page_delegate_impl.h',
       'browser/ui/omnibox/omnibox_edit_controller.cc',
       'browser/ui/omnibox/omnibox_edit_controller.h',
       'browser/ui/omnibox/omnibox_edit_model.cc',
@@ skipping 854 matching lines @@
       'browser/ui/views/message_center/message_center_widget_delegate.cc',
       'browser/ui/views/message_center/web_notification_tray.h',
       'browser/ui/views/message_center/web_notification_tray.cc',
       'browser/ui/views/message_center/web_notification_tray_win.cc',
       'browser/ui/views/screen_capture_notification_ui_views.cc',
     ],
     # Cross-platform aura sources.
     'chrome_browser_ui_aura_sources': [
       'browser/ui/aura/chrome_browser_main_extra_parts_aura.cc',
       'browser/ui/aura/chrome_browser_main_extra_parts_aura.h',
+      'browser/ui/aura/native_window_tracker_aura.cc',
+      'browser/ui/aura/native_window_tracker_aura.h',
       'browser/ui/aura/tab_contents/web_drag_bookmark_handler_aura.cc',
       'browser/ui/aura/tab_contents/web_drag_bookmark_handler_aura.h',
       'browser/ui/gesture_prefs_observer_factory_aura.cc',
       'browser/ui/gesture_prefs_observer_factory_aura.h',
       'browser/ui/views/link_disambiguation/link_disambiguation_popup.cc',
       'browser/ui/views/link_disambiguation/link_disambiguation_popup.h',
       'browser/ui/webui/gesture_config_ui.cc',
       'browser/ui/webui/gesture_config_ui.h',
       'browser/ui/window_sizer/window_sizer_aura.cc',
     ],
@@ skipping 721 matching lines @@
         ['OS!="android" and OS!="ios"', {
           'dependencies': [
             '../device/bluetooth/bluetooth.gyp:device_bluetooth',
           ],
           'sources': [ '<@(chrome_browser_ui_non_mobile_sources)' ],
         }],
       ],
     },
   ],
 }