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

ash/common/accelerators/accelerator_controller.cc

Index: ash/common/accelerators/accelerator_controller.cc
diff --git a/ash/common/accelerators/accelerator_controller.cc b/ash/common/accelerators/accelerator_controller.cc
index ef5c7a35a53c28bbc2c95142087066724dde609d..06233492911adac5de255aed34f51df67fdd24f1 100644
--- a/ash/common/accelerators/accelerator_controller.cc
+++ b/ash/common/accelerators/accelerator_controller.cc
@@ -33,6 +33,7 @@
 #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"
@@ -924,12 +925,12 @@ bool AcceleratorController::ShouldActionConsumeKeyEvent(
 
 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()) {
@@ -960,6 +961,13 @@ AcceleratorController::GetAcceleratorProcessingRestriction(int action) {
         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;
 }