Work on separate browser contexts

ui/gfx/screen.h

Index: ui/gfx/screen.h
diff --git a/ui/gfx/screen.h b/ui/gfx/screen.h
index 7e979c4f28c8db8a268a3ac6e58dffac30c95cd8..580fde9349f7dc97a4f3a9dcebc8478c20bdfc98 100644
--- a/ui/gfx/screen.h
+++ b/ui/gfx/screen.h
@@ -30,6 +30,10 @@ class UI_EXPORT Screen {
   // ScreenType must be provided.
   static void SetScreenInstance(ScreenType type, Screen* instance);
 
+  // Returns the global screen for a particular type. Types other than _NATIVE
+  // may be NULL.
+  static Screen* GetScreenByType(ScreenType type);
+
   // Sets the global ScreenTypeDelegate. May be left unset if the platform
   // uses only the _NATIVE ScreenType.
   static void SetScreenTypeDelegate(ScreenTypeDelegate* delegate);