The key event should be stopped propagation when it's been processed as an accelerator.

ui/views/widget/native_widget_aura.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/views/widget/native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "third_party/skia/include/core/SkRegion.h"
@@ skipping 857 matching lines @@
 
 void NativeWidgetAura::OnKeyEvent(ui::KeyEvent* event) {
   DCHECK(window_);
   // Renderer may send a key event back to us if the key event wasn't handled,
   // and the window may be invisible by that time.
   if (!window_->IsVisible())
     return;
 
   FocusManager* focus_manager = GetWidget()->GetFocusManager();
   delegate_->OnKeyEvent(event);
-  if (!event->handled() && focus_manager)
-    focus_manager->OnKeyEvent(*event);
+  if (!event->handled() && focus_manager) {
+    if (!focus_manager->OnKeyEvent(*event))
+      event->StopPropagation();
+  }

[sadrul, 2016/02/17 21:17:55]

Should this code just move into Widget::OnKeyEvent()? That way, we don't need to
duplicate this code in NWA and DNWA (and also in NativeWidgetMus)

[Shu Chen, 2016/02/18 00:29:54]

Done. Good idea.

   event->SetHandled();
 }
 
 void NativeWidgetAura::OnMouseEvent(ui::MouseEvent* event) {
   DCHECK(window_);
   DCHECK(window_->IsVisible());
   if (event->type() == ui::ET_MOUSEWHEEL) {
     delegate_->OnMouseEvent(event);
     if (event->handled())
       return;
@@ skipping 280 matching lines @@
   l10n_util::AdjustUIFont(&(ncm.lfCaptionFont));
   base::win::ScopedHFONT caption_font(CreateFontIndirect(&(ncm.lfCaptionFont)));
   return gfx::FontList(gfx::Font(caption_font.get()));
 #else
   return gfx::FontList();
 #endif
 }
 
 }  // namespace internal
 }  // namespace views