cros: Fix clusterfuzz crash when spawning app list very early in startup

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 251 matching lines @@
 }
 
 void HandleSwitchIme(ImeControlDelegate* ime_control_delegate,
                      const ui::Accelerator& accelerator) {
   base::RecordAction(UserMetricsAction("Accel_Switch_Ime"));
   ime_control_delegate->HandleSwitchIme(accelerator);
 }
 
 bool CanHandleToggleAppList(const ui::Accelerator& accelerator,
                             const ui::Accelerator& previous_accelerator) {
+  // Some tests try to spawn the app list before the shelf is created, but the
+  // app list depends on the shelf for positioning. Users never open the app

[msw, 2017/01/05 00:41:34]

The app list doesn't actually depend on the shelf for positioning (at least not
in practice anymore, afaik...). Perhaps we can remove any vestiges of that
dependency to avoid this crash?

+  // list that early, so disable showing it. http://crbug.com/676843
+  WmWindow* target_root = WmShell::Get()->GetRootWindowForNewWindows();
+  if (!WmShelf::ForWindow(target_root)->IsShelfInitialized())
+    return false;
+
   if (accelerator.key_code() == ui::VKEY_LWIN) {
     // If something else was pressed between the Search key (LWIN)
     // being pressed and released, then ignore the release of the
     // Search key.
     if (previous_accelerator.type() != ui::ET_KEY_PRESSED ||
         previous_accelerator.key_code() != ui::VKEY_LWIN) {
       return false;
     }
 
     // When spoken feedback is enabled, we should neither toggle the list nor
@@ skipping 886 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