Improves first run dialog performance on Win8

chrome/chrome_browser_ui.gypi

Index: chrome/chrome_browser_ui.gypi
diff --git a/chrome/chrome_browser_ui.gypi b/chrome/chrome_browser_ui.gypi
index 48e5e44d8665f463313007e0ba8848ea9deb2875..1295e04f3702bf28c1dd8c773e84810552c257b9 100644
--- a/chrome/chrome_browser_ui.gypi
+++ b/chrome/chrome_browser_ui.gypi
@@ -2589,8 +2589,8 @@
       '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': [