Relanding the EventTarget fixes for Aura (Ash) as the previous attempt was reverted due to interact…

ui/aura/root_window.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/aura/root_window.h"
 
 #include <vector>
 
 #include "base/auto_reset.h"
 #include "base/bind.h"
@@ skipping 434 matching lines @@
   // If the layer is not animating, then we need to update the host size
   // immediately.
   if (!layer()->GetAnimator()->is_animating())
     OnHostResized(host_->GetBounds().size());
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RootWindow, ui::EventTarget implementation:
 
 ui::EventTarget* RootWindow::GetParentTarget() {
-  return Env::GetInstance();
+  return client::GetEventClient(this) ?
+      client::GetEventClient(this)->GetToplevelEventTarget() :
+          Env::GetInstance();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // RootWindow, ui::CompositorDelegate implementation:
 
 void RootWindow::ScheduleDraw() {
   if (!defer_draw_scheduling_) {
     defer_draw_scheduling_ = true;
     MessageLoop::current()->PostTask(
         FROM_HERE,
@@ skipping 561 matching lines @@
   ui::MouseEvent event(ui::ET_MOUSE_MOVED,
                        orig_mouse_location,
                        orig_mouse_location,
                        ui::EF_IS_SYNTHESIZED);
   event.set_system_location(Env::GetInstance()->last_mouse_location());
   OnHostMouseEvent(&event);
 #endif
 }
 
 }  // namespace aura