Enable display rotation, magnifier in unified desktop mode

ash/display/display_manager.h

Index: ash/display/display_manager.h
diff --git a/ash/display/display_manager.h b/ash/display/display_manager.h
index d875efb3f2ae9eb186d6d45b6b74e0f4b3d97879..e7711a05865670d6e54968f85b36bbd1a6c6f21d 100644
--- a/ash/display/display_manager.h
+++ b/ash/display/display_manager.h
@@ -292,7 +292,7 @@ class ASH_EXPORT DisplayManager
   void SetMultiDisplayMode(MultiDisplayMode mode);
 
   // Sets/gets default multi display mode.
-
+  void SetDefaultMultiDisplayMode(MultiDisplayMode mode);

[Jun Mukai, 2015/05/01 22:06:07]

What is the motivation to make this public again?
Still only test code invokes this, so I think it's still okay to be in the test
api.

[oshima, 2015/05/01 22:44:57]

Turns out that this needs to be configurable. About flags will be used to
control if this option is available in the settings.

   MultiDisplayMode default_multi_display_mode() const {
     return default_multi_display_mode_;
   }