Fix code around display overscan settings.

ash/display/multi_display_manager.cc

Index: ash/display/multi_display_manager.cc
diff --git a/ash/display/multi_display_manager.cc b/ash/display/multi_display_manager.cc
index 5cb7cfd0bbc06a46693aeb70983573c86bd65757..3280583162fda61de4f5130cbd9e5f2a9d22a88d 100644
--- a/ash/display/multi_display_manager.cc
+++ b/ash/display/multi_display_manager.cc
@@ -197,11 +197,8 @@ void MultiDisplayManager::OnNativeDisplaysChanged(
        iter != new_displays.end(); ++iter) {
     std::map<int64, gfx::Insets>::const_iterator overscan_insets =
         overscan_mapping_.find(iter->id());
-    if (overscan_insets != overscan_mapping_.end()) {
-      gfx::Rect bounds = iter->bounds_in_pixel();
-      bounds.Inset(overscan_insets->second.Scale(iter->device_scale_factor()));
-      iter->SetScaleAndBounds(iter->device_scale_factor(), bounds);
-    }
+    if (overscan_insets != overscan_mapping_.end())
+      iter->SetOverscanInsets(overscan_insets->second);
   }
 
   std::sort(displays_.begin(), displays_.end(), DisplaySortFunctor());