Add ctrl+drag feature for allowing resizing window with exact positioning.

ash/wm/toplevel_window_event_filter.cc

Index: ash/wm/toplevel_window_event_filter.cc
diff --git a/ash/wm/toplevel_window_event_filter.cc b/ash/wm/toplevel_window_event_filter.cc
index 962698ffdade5ab297f36423acee5d9175dce57b..5eb7f9add32ecb0b04cacf1e034cec74395f0b93 100644
--- a/ash/wm/toplevel_window_event_filter.cc
+++ b/ash/wm/toplevel_window_event_filter.cc
@@ -215,7 +215,8 @@ bool ToplevelWindowEventFilter::HandleDrag(aura::Window* target,
 
   if (!window_resizer_.get())
     return false;
-  window_resizer_->Drag(ConvertPointToParent(target, event->location()));
+  window_resizer_->Drag(ConvertPointToParent(target, event->location()),
+                        event->flags());
   return true;
 }