Refuse to show Alt+Tab UI concurrently with virtual keyboard.

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 "ash/common/accelerators/accelerator_commands.h"
 #include "ash/common/accelerators/accelerator_controller_delegate.h"
 #include "ash/common/accelerators/debug_commands.h"
 #include "ash/common/accessibility_delegate.h"
@@ skipping 15 matching lines @@
 #include "ash/common/wm/window_cycle_controller.h"
 #include "ash/common/wm/window_positioning_utils.h"
 #include "ash/common/wm/window_state.h"
 #include "ash/common/wm/wm_event.h"
 #include "ash/common/wm_shell.h"
 #include "ash/common/wm_window.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/user_metrics.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/accelerators/accelerator_manager.h"
+#include "ui/keyboard/keyboard_controller.h"
 
 #if defined(OS_CHROMEOS)
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "chromeos/dbus/power_manager_client.h"
 #include "ui/base/ime/chromeos/ime_keyboard.h"
 #include "ui/base/ime/chromeos/input_method_manager.h"
 #endif  // defined(OS_CHROMEOS)
 
 namespace ash {
 namespace {
@@ skipping 870 matching lines @@
   }
 }
 
 bool AcceleratorController::ShouldActionConsumeKeyEvent(
     AcceleratorAction action) {
   // Adding new exceptions is *STRONGLY* discouraged.
   return true;
 }
 
 AcceleratorController::AcceleratorProcessingRestriction
 AcceleratorController::GetAcceleratorProcessingRestriction(int action) {

[varkha, 2016/08/22 20:59:23]

Maybe deserves a followup. Is there a good reason that action is not stronger
typed? I have noticed some call to this method with action=-1. Is that the
reason? Could that -1 be turned into another value in the enum?

[Evan Stade, 2016/08/22 21:35:04]

dunno, seems tangential to this CL though.

-  if (WmShell::Get()->IsPinned() &&
+  WmShell* wm_shell = WmShell::Get();
+  if (wm_shell->IsPinned() &&
       actions_allowed_in_pinned_mode_.find(action) ==
           actions_allowed_in_pinned_mode_.end()) {
     return RESTRICTION_PREVENT_PROCESSING_AND_PROPAGATION;
   }
-  WmShell* wm_shell = WmShell::Get();
   if (!wm_shell->GetSessionStateDelegate()->IsActiveUserSessionStarted() &&
       actions_allowed_at_login_screen_.find(action) ==
           actions_allowed_at_login_screen_.end()) {
     return RESTRICTION_PREVENT_PROCESSING;
   }
   if (wm_shell->GetSessionStateDelegate()->IsScreenLocked() &&
       actions_allowed_at_lock_screen_.find(action) ==
           actions_allowed_at_lock_screen_.end()) {
     return RESTRICTION_PREVENT_PROCESSING;
   }
@@ skipping 10 matching lines @@
     // Alt+Tab that would cause an undesired effect in the modal window by
     // cycling through its window elements.
     return RESTRICTION_PREVENT_PROCESSING_AND_PROPAGATION;
   }
   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;
   }
+  // 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();
+  if (keyboard_controller && keyboard_controller->keyboard_visible())
+    return RESTRICTION_PREVENT_PROCESSING;

[oshima, 2016/08/18 23:53:31]

This disable alt-tab even if I used the real keyboard when VK is visible.
varkha@, bshe@ is there any good way to tell if this is coming from VK?

If it's hard, then I'm fine.

[varkha, 2016/08/22 20:59:23]

Maybe we can plumb through a ui::Accelerator parameter and get some knowledge
from that where the event originated.

[bshe, 2016/08/22 21:02:56]

If alt + tab is disabled for VK, it is probably better to disable it in vk code.
This way, it wont affect real keyboard.  +wuyingbing

[Evan Stade, 2016/08/22 21:35:04]

seems very not worth it. Why is a user using both keyboards at the same time?

[Evan Stade, 2016/08/22 21:35:04]

How would one do that? By special casing to ignore alt+tab? That doesn't sound
appealing. That said, yes, fixing the virtual keyboard to behave more like a
real keyboard is one viable alternative (see discussion on bug).

+
   return RESTRICTION_NONE;
 }
 
 }  // namespace ash