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

ui/views/widget/widget.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/widget.h"
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 1144 matching lines @@
       HTNOWHERE;
 
   if (movement_disabled_ && (component == HTCAPTION || component == HTSYSMENU))
     return HTNOWHERE;
 
   return component;
 }
 
 void Widget::OnKeyEvent(ui::KeyEvent* event) {
   SendEventToProcessor(event);
+  if (!event->handled() && GetFocusManager() &&
+      !GetFocusManager()->OnKeyEvent(*event)) {
+    event->StopPropagation();
+  }
 }
 
 // TODO(tdanderson): We should not be calling the OnMouse*() functions on
 //                   RootView from anywhere in Widget. Use
 //                   SendEventToProcessor() instead. See crbug.com/348087.
 void Widget::OnMouseEvent(ui::MouseEvent* event) {
   View* root_view = GetRootView();
   switch (event->type()) {
     case ui::ET_MOUSE_PRESSED: {
       last_mouse_event_was_move_ = false;
@@ skipping 312 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views