make StackingClient dispatch to either ash or desktop

chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc

Index: chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
diff --git a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
index 73b1d439fb452e32ef171cb8c18e12d3dcad1a76..230a07d519139dfa39de941ee2aa5abdfbbd3ae7 100644
--- a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
+++ b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.cc
@@ -16,6 +16,8 @@
 #if defined(OS_LINUX)
 #include "chrome/browser/ui/libgtk2ui/gtk2_ui.h"
 #include "ui/base/linux_ui.h"
+#else
+#include "chrome/browser/ui/aura/stacking_client_aurawin.h"
 #endif
 
 #if defined(USE_ASH)
@@ -37,7 +39,12 @@ void ChromeBrowserMainExtraPartsAura::PreProfileInit() {
     gfx::Screen::SetScreenInstance(
         gfx::SCREEN_TYPE_NATIVE, aura::CreateDesktopScreen());
     aura::Env::GetInstance()->SetDisplayManager(new aura::SingleDisplayManager);
+#if defined(OS_LINUX)
     stacking_client_.reset(new aura::DesktopStackingClient);
+#else
+    stacking_client_.reset(new StackingClientAuraWin);

[Ben Goodger (Google), 2012/11/12 16:49:33]

is there any reason we can't use this on windows too? it doesn't look inherently
windows specific. i'd rather keep this code as cross-platform as possible.

[scottmg, 2012/11/12 18:03:53]

Done. ("can't use this on linux too?" i assume)

+#endif
+    aura::client::SetStackingClient(stacking_client_.get());
   }
 #endif