Do not activate system tray bubble by default

ash/aura/wm_shell_aura.cc

 // Copyright 2016 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 "ash/aura/wm_shell_aura.h"
 
 #include <utility>
 
+#include "ash/aura/key_event_watcher_aura.h"
 #include "ash/aura/pointer_watcher_adapter.h"
 #include "ash/aura/wm_window_aura.h"
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shell_delegate.h"
 #include "ash/common/shell_observer.h"
 #include "ash/common/wm/maximize_mode/scoped_disable_internal_mouse_and_keyboard.h"
 #include "ash/common/wm/mru_window_tracker.h"
 #include "ash/common/wm/overview/window_selector_controller.h"
 #include "ash/common/wm_activation_observer.h"
 #include "ash/common/wm_display_observer.h"
@@ skipping 203 matching lines @@
   return base::WrapUnique(new ScopedDisableInternalMouseAndKeyboardOzone);
 #endif
   return nullptr;
 }
 
 std::unique_ptr<ImmersiveFullscreenController>
 WmShellAura::CreateImmersiveFullscreenController() {
   return base::MakeUnique<ImmersiveFullscreenController>();
 }
 
+std::unique_ptr<KeyEventWatcher> WmShellAura::CreateKeyEventWatcher() {
+  return base::MakeUnique<KeyEventWatcherAura>();
+}
+
 void WmShellAura::OnOverviewModeStarting() {
   FOR_EACH_OBSERVER(ShellObserver, *shell_observers(),
                     OnOverviewModeStarting());
 }
 
 void WmShellAura::OnOverviewModeEnded() {
   FOR_EACH_OBSERVER(ShellObserver, *shell_observers(), OnOverviewModeEnded());
 }
 
 SessionStateDelegate* WmShellAura::GetSessionStateDelegate() {
@@ skipping 73 matching lines @@
   FOR_EACH_OBSERVER(WmDisplayObserver, display_observers_,
                     OnDisplayConfigurationChanging());
 }
 
 void WmShellAura::OnDisplayConfigurationChanged() {
   FOR_EACH_OBSERVER(WmDisplayObserver, display_observers_,
                     OnDisplayConfigurationChanged());
 }
 
 }  // namespace ash