Reland fast tab closure behind a flag

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.
 
 {
   'targets': [
     {
       'target_name': 'browser_ui',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 943 matching lines @@
         'browser/ui/extensions/extension_install_ui_default.cc',
         'browser/ui/extensions/extension_install_ui_default.h',
         'browser/ui/extensions/extension_enable_flow.cc',
         'browser/ui/extensions/extension_enable_flow.h',
         'browser/ui/extensions/extension_enable_flow_delegate.h',
         'browser/ui/extensions/native_app_window.h',
         'browser/ui/extensions/shell_window.cc',
         'browser/ui/extensions/shell_window.h',
         'browser/ui/external_protocol_dialog_delegate.cc',
         'browser/ui/external_protocol_dialog_delegate.h',
+        'browser/ui/fast_unload_controller.cc',
+        'browser/ui/fast_unload_controller.h',
         'browser/ui/find_bar/find_bar.h',
         'browser/ui/find_bar/find_bar_controller.cc',
         'browser/ui/find_bar/find_bar_controller.h',
         'browser/ui/find_bar/find_bar_state.h',
         'browser/ui/find_bar/find_bar_state_factory.cc',
         'browser/ui/find_bar/find_bar_state_factory.h',
         'browser/ui/find_bar/find_notification_details.h',
         'browser/ui/find_bar/find_tab_helper.cc',
         'browser/ui/find_bar/find_tab_helper.h',
         'browser/ui/fullscreen/fullscreen_controller.cc',
@@ skipping 600 matching lines @@
         'browser/ui/views/chrome_views_delegate_chromeos.cc',
         'browser/ui/views/chrome_web_dialog_view.cc',
         'browser/ui/views/collected_cookies_views.cc',
         'browser/ui/views/collected_cookies_views.h',
         'browser/ui/views/color_chooser_aura.cc',
         'browser/ui/views/color_chooser_dialog.cc',
         'browser/ui/views/color_chooser_dialog.h',
         'browser/ui/views/color_chooser_win.cc',
         'browser/ui/views/confirm_bubble_views.cc',
         'browser/ui/views/confirm_bubble_views.h',
-        'browser/ui/views/conflicting_module_view_win.cc',  
-        'browser/ui/views/conflicting_module_view_win.h',  
+        'browser/ui/views/conflicting_module_view_win.cc',
+        'browser/ui/views/conflicting_module_view_win.h',
         'browser/ui/views/constrained_web_dialog_delegate_views.cc',
         'browser/ui/views/constrained_window_views.cc',
         'browser/ui/views/constrained_window_views.h',
         'browser/ui/views/content_setting_bubble_contents.cc',
         'browser/ui/views/content_setting_bubble_contents.h',
         'browser/ui/views/cookie_info_view.cc',
         'browser/ui/views/cookie_info_view.h',
         'browser/ui/views/create_application_shortcut_view.cc',
         'browser/ui/views/create_application_shortcut_view.h',
         'browser/ui/views/crypto_module_password_dialog_view.cc',
@@ skipping 1414 matching lines @@
         ['enable_google_now==0', {
           'sources!': [
             'browser/ui/webui/options/geolocation_options_handler.cc',
             'browser/ui/webui/options/geolocation_options_handler.h',
           ],
         }],
       ],
     },
   ],
 }