Remove TransparentActivateWindowButton from Overview Mode

ash/wm/panels/panel_window_event_handler.cc

 // Copyright 2013 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/panels/panel_window_event_handler.h"
 
 #include "ash/metrics/user_metrics_recorder.h"
 #include "ash/shell.h"
 #include "ash/wm/window_state.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/base/hit_test.h"
 #include "ui/events/event.h"
 
 namespace ash {
 
 PanelWindowEventHandler::PanelWindowEventHandler() {
 }
 
 PanelWindowEventHandler::~PanelWindowEventHandler() {
 }
 
 void PanelWindowEventHandler::OnMouseEvent(ui::MouseEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
   if (!event->handled() &&
       event->type() == ui::ET_MOUSE_PRESSED &&
       event->flags() & ui::EF_IS_DOUBLE_CLICK &&
       event->IsOnlyLeftMouseButton() &&
+      target->delegate() &&

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

Without this change, this code crashed when handling events in the overview due
to the container windows having no delegate

       target->delegate()->GetNonClientComponent(event->location()) ==
           HTCAPTION) {
     ash::Shell::GetInstance()->metrics()->RecordUserMetricsAction(
         ash::UMA_PANEL_MINIMIZE_CAPTION_CLICK);
     wm::GetWindowState(target)->Minimize();
     event->StopPropagation();
     return;
   }
 }
 
 void PanelWindowEventHandler::OnGestureEvent(ui::GestureEvent* event) {
   aura::Window* target = static_cast<aura::Window*>(event->target());
   if (!event->handled() &&
       event->type() == ui::ET_GESTURE_TAP &&
       event->details().tap_count() == 2 &&
+      target->delegate() &&

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

Same as L29

       target->delegate()->GetNonClientComponent(event->location()) ==
           HTCAPTION) {
     ash::Shell::GetInstance()->metrics()->RecordUserMetricsAction(
         ash::UMA_PANEL_MINIMIZE_CAPTION_GESTURE);
     wm::GetWindowState(target)->Minimize();
     event->StopPropagation();
     return;
   }
 }
 
 }  // namespace ash