[zoom bubble] Add tests for ZoomController::UpdateState() handling empty hosts.

chrome/browser/ui/zoom/zoom_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 "chrome/browser/ui/zoom/zoom_controller.h"
 
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/common/chrome_notification_types.h"
@@ skipping 22 matching lines @@
                                       std::string()));
 
   content::HostZoomMap* zoom_map =
       content::HostZoomMap::GetForBrowserContext(profile);
   registrar_.Add(this, content::NOTIFICATION_ZOOM_LEVEL_CHANGED,
                  content::Source<content::HostZoomMap>(zoom_map));
 
   UpdateState(std::string());
 }
 
-ZoomController::~ZoomController() {
-  default_zoom_level_.Destroy();
-  registrar_.RemoveAll();
-}
+ZoomController::~ZoomController() {}
 
 bool ZoomController::IsAtDefaultZoom() const {
   return content::ZoomValuesEqual(web_contents()->GetZoomLevel(),
                                   default_zoom_level_.GetValue());
 }
 
 int ZoomController::GetResourceForZoomLevel() const {
   DCHECK(!IsAtDefaultZoom());
   double zoom = web_contents()->GetZoomLevel();
   return zoom > default_zoom_level_.GetValue() ? IDR_ZOOM_PLUS : IDR_ZOOM_MINUS;
@@ skipping 28 matching lines @@
       return;
     }
   }
 
   bool dummy;
   zoom_percent_ = web_contents()->GetZoomPercent(&dummy, &dummy);
 
   if (observer_)
     observer_->OnZoomChanged(web_contents(), !host.empty());
 }