Makes the frame maximize button show the multi-state icon on hover.

ash/wm/workspace/frame_maximize_button.cc

Index: ash/wm/workspace/frame_maximize_button.cc
diff --git a/ash/wm/workspace/frame_maximize_button.cc b/ash/wm/workspace/frame_maximize_button.cc
index 49e4a611fa5f347677a50cdbd0e13c912a890306..f4572d3684ddd7411b3ef6f96285a47388e1b40d 100644
--- a/ash/wm/workspace/frame_maximize_button.cc
+++ b/ash/wm/workspace/frame_maximize_button.cc
@@ -213,6 +213,9 @@ SkBitmap FrameMaximizeButton::GetImageToPaint() {
       }
     }
     return *ResourceBundle::GetSharedInstance().GetImageNamed(id).ToSkBitmap();
+  } else if (state() == BS_HOT) {
+    return *ResourceBundle::GetSharedInstance().GetImageNamed(
+        IDR_AURA_WINDOW_MAXIMIZED_RESTORE_SNAP_P).ToSkBitmap();
   }
   return ImageButton::GetImageToPaint();
 }