Improves first run dialog performance on Win8

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': {
     # There are two sections of sources:
     # * "Platform"-based sources (OS, toolkit, etc.)
     # * Feature/directory-based sources (e.g., history, printing)
 
@@ skipping 2571 matching lines @@
       'browser/ui/views/frame/glass_browser_frame_view.cc',
       'browser/ui/views/frame/glass_browser_frame_view.h',
       'browser/ui/views/frame/native_browser_frame_factory_aurawin.cc',
       'browser/ui/views/network_profile_bubble_view.cc',
       'browser/ui/views/uninstall_view.cc',
       'browser/ui/views/uninstall_view.h',
       'browser/ui/webui/cast/cast_ui.cc',
       'browser/ui/webui/cast/cast_ui.h',
       'browser/ui/webui/conflicts_ui.cc',
       'browser/ui/webui/conflicts_ui.h',
-      'browser/ui/webui/set_as_default_browser_ui.cc',
-      'browser/ui/webui/set_as_default_browser_ui.h',
+      'browser/ui/webui/set_as_default_browser_ui_win.cc',

[grt (UTC plus 2), 2016/07/19 08:13:01]

while this is win-only, i'm inclined to put it in a more general variable and
let the _win filtering take care of it. sky: what's your opinion here?

[zmin, 2016/07/20 16:35:45]

Done.
I didn't know there is a _win filter. I think we shall use that filter if there
is _win suffix.

[grt (UTC plus 2), 2016/07/20 18:54:09]

Magic!
(https://cs.chromium.org/chromium/src/build/config/BUILDCONFIG.gn?dr=C&q=%5C*_...)

+      'browser/ui/webui/set_as_default_browser_ui_win.h',
     ],
     # Compiled for X11: desktop Linux and ChromeOS. We assume aura/views/ash.
     'chrome_browser_ui_x11_sources': [
       'browser/ui/views/javascript_app_modal_event_blocker_x11.cc',
       'browser/ui/views/javascript_app_modal_event_blocker_x11.h',
       'browser/ui/views/tabs/window_finder_x11.cc',
     ],
 
     ### Feature-based sources ###
     # Variables should generally be alphabetical within this section.
@@ skipping 769 matching lines @@
           ],
           'sources': [
             '<@(chrome_browser_ui_non_mobile_sources)',
             '<@(chrome_browser_ui_omnibox_non_mobile_sources)',
           ],
         }],
       ],
     },
   ],
 }