Remove TransparentActivateWindowButton from Overview Mode

ash/wm/workspace/workspace_event_handler.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/wm/workspace/workspace_event_handler.h"
 
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/shell.h"
 #include "ash/touch/touch_uma.h"
 #include "ash/wm/window_state.h"
 #include "ash/wm/wm_event.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/base/hit_test.h"
 
 namespace ash {
 
 WorkspaceEventHandler::WorkspaceEventHandler()
     : click_component_(HTNOWHERE) {
 }
 
 WorkspaceEventHandler::~WorkspaceEventHandler() {
 }
 
 void WorkspaceEventHandler::OnMouseEvent(ui::MouseEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
+
+  if (!target->delegate())

[Nina, 2015/01/09 15:43:49]

Without the change, this code would crash if the user clicked, switched to
overview and quickly clicked again.

+    return;
+
   if (event->type() == ui::ET_MOUSE_PRESSED &&
       event->IsOnlyLeftMouseButton() &&
       ((event->flags() &
           (ui::EF_IS_DOUBLE_CLICK | ui::EF_IS_TRIPLE_CLICK)) == 0)) {
     click_component_ = target->delegate()->
         GetNonClientComponent(event->location());
   }
 
   if (event->handled())
     return;
@@ skipping 38 matching lines @@
     default:
       break;
   }
 }
 
 void WorkspaceEventHandler::OnGestureEvent(ui::GestureEvent* event) {
   if (event->handled() || event->type() != ui::ET_GESTURE_TAP)
     return;
 
   aura::Window* target = static_cast<aura::Window*>(event->target());
+
+  if (!target->delegate())
+    return;
+
   int previous_target_component = click_component_;
   click_component_ = target->delegate()->
       GetNonClientComponent(event->location());
 
   if (click_component_ != HTCAPTION)
     return;
 
   if (event->details().tap_count() != 2) {
     TouchUMA::GetInstance()->
         RecordGestureAction(TouchUMA::GESTURE_FRAMEVIEW_TAP);
@@ skipping 29 matching lines @@
       Shell::GetInstance()->metrics()->RecordUserMetricsAction(
           UMA_TOGGLE_SINGLE_AXIS_MAXIMIZE_BORDER_CLICK);
       const wm::WMEvent wm_event(wm::WM_EVENT_TOGGLE_HORIZONTAL_MAXIMIZE);
       target_state->OnWMEvent(&wm_event);
       event->StopPropagation();
     }
   }
 }
 
 }  // namespace ash