reland of https://codereview.chromium.org/11364053/ w/o removing the per-rootwindow stacking client

chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h

Index: chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
diff --git a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
index 199279bdc12a770c0c363ffb33947a7b484b5710..3f0784ae87cb7ebc9c265a222e0cf2fb5be2c7d4 100644
--- a/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
+++ b/chrome/browser/ui/aura/chrome_browser_main_extra_parts_aura.h
@@ -11,7 +11,9 @@
 #include "chrome/browser/chrome_browser_main_extra_parts.h"
 
 namespace aura {
-class DesktopStackingClient;
+namespace client {
+class StackingClient;
+}
 }
 
 class ChromeBrowserMainExtraPartsAura : public ChromeBrowserMainExtraParts {
@@ -24,7 +26,7 @@ class ChromeBrowserMainExtraPartsAura : public ChromeBrowserMainExtraParts {
   virtual void PostMainMessageLoopRun() OVERRIDE;
 
  private:
-  scoped_ptr<aura::DesktopStackingClient> stacking_client_;
+  scoped_ptr<aura::client::StackingClient> stacking_client_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainExtraPartsAura);
 };