Try to enable software mirror mode in UI message loop after Init()

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 93c203b9a5d67c6a5136cbaa1639712f6deffead..d905f7c1dcf5c641d983f418bbb156223d2a5a10 100644
--- a/ash/display/display_manager.h
+++ b/ash/display/display_manager.h
@@ -217,10 +217,18 @@ class ASH_EXPORT DisplayManager
 #else
   void SetSoftwareMirroring(bool enabled);
 #endif
+  bool software_mirroring_enabled() const {
+    return software_mirroring_enabled_;
+  };
 
   // Update the bounds of the display given by |display_id|.
   bool UpdateDisplayBounds(int64 display_id,
                            const gfx::Rect& new_bounds);
+
+  // Creates mirror window if the software mirror mode is enabled.
+  // This is used only for bootstrap.
+  void CreateMirrorWindowIfAny();
+
 private:
   FRIEND_TEST_ALL_PREFIXES(ExtendedDesktopTest, ConvertPoint);
   FRIEND_TEST_ALL_PREFIXES(DisplayManagerTest, TestNativeDisplaysChanged);