Don't mark virtual keyboard events as synthesized or distinguish between

ash/common/accelerators/accelerator_controller.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 "ash/common/accelerators/accelerator_controller.h"
 
 #include <utility>
 
 #include "ash/common/accelerators/accelerator_commands.h"
 #include "ash/common/accelerators/accelerator_controller_delegate.h"
@@ skipping 155 matching lines @@
 
 bool CanHandleNextIme(ImeControlDelegate* ime_control_delegate) {
   return ime_control_delegate && ime_control_delegate->CanCycleIme();
 }
 
 bool CanHandleCycleMru(const ui::Accelerator& accelerator) {
   // Don't do anything when Alt+Tab comes from a virtual keyboard. Touchscreen
   // users have better window switching options. See http://crbug.com/638269
   keyboard::KeyboardController* keyboard_controller =
       keyboard::KeyboardController::GetInstance();
-  return !(keyboard_controller && keyboard_controller->keyboard_visible() &&
-           (accelerator.modifiers() & ui::EF_IS_SYNTHESIZED));
+  return !(keyboard_controller && keyboard_controller->keyboard_visible());

[oshima, 2017/01/05 22:11:35]

Hmm that's unfortunate.

Could you please add comment that this will disable alt-tab on real keyboard
when it's visible, but it's WAI due to IME implementation?

[Evan Stade, 2017/01/06 19:37:51]

Done.

 }
 
 // We must avoid showing the Deprecated NEXT_IME notification erronously.
 bool ShouldShowDeprecatedNextImeNotification(
     const ui::Accelerator& previous_accelerator) {
   // We only show the deprecation notification if the previous accelerator key
   // is ONLY either Shift, or Alt.
   const ui::KeyboardCode previous_key_code = previous_accelerator.key_code();
   switch (previous_key_code) {
     case ui::VKEY_SHIFT:
@@ skipping 980 matching lines @@
   if (wm_shell->mru_window_tracker()->BuildMruWindowList().empty() &&
       actions_needing_window_.find(action) != actions_needing_window_.end()) {
     wm_shell->accessibility_delegate()->TriggerAccessibilityAlert(
         A11Y_ALERT_WINDOW_NEEDED);
     return RESTRICTION_PREVENT_PROCESSING_AND_PROPAGATION;
   }
   return RESTRICTION_NONE;
 }
 
 }  // namespace ash