Add Mouse hover behavior to Mac Panels when minimized

chrome/browser/ui/panels/panel_mouse_watcher.cc

 // Copyright (c) 2011 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 "chrome/browser/ui/panels/panel_mouse_watcher.h"
 
 #include "chrome/browser/ui/panels/panel_manager.h"
 
 PanelMouseWatcher::PanelMouseWatcher()
     : bring_up_titlebar_(false), is_testing_mode_enabled_(false) {
 }
 
 PanelMouseWatcher::~PanelMouseWatcher() {
+  DCHECK(subscribers_.size() == 0);
 }
 
 void PanelMouseWatcher::AddSubscriber(NativePanel* native_panel) {
   if (is_testing_mode_enabled_)
     return;
 
   if (subscribers_.count(native_panel) == 0) {
     subscribers_.insert(native_panel);
     DCHECK_LE(subscribers_.size(),
               static_cast<size_t>(PanelManager::GetInstance()->num_panels()));
@@ skipping 28 matching lines @@
   PanelManager* panel_manager = PanelManager::GetInstance();
 
   bool bring_up_titlebar =
       panel_manager->ShouldBringUpTitlebars(
           mouse_position.x(), mouse_position.y());
   if (bring_up_titlebar == bring_up_titlebar_)
     return;
   bring_up_titlebar_ = bring_up_titlebar;
   panel_manager->BringUpOrDownTitlebars(bring_up_titlebar);
 }