Task Manager: overhaul & re-enable task manager browser tests.

chrome/browser/task_manager/notification_resource_provider.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/task_manager/notification_resource_provider.h"
 
 #include "base/strings/string16.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/devtools/devtools_window.h"
@@ skipping 187 matching lines @@
       RemoveFromTaskManager(content::Source<BalloonHost>(source).ptr());
       break;
     default:
       NOTREACHED() << "Unexpected notification.";
       return;
   }
 }
 
 void NotificationResourceProvider::AddToTaskManager(
     BalloonHost* balloon_host) {
+  // The resource may already be tracked, if the task manager was opened
+  // while the BalloonHost was waiting to connect.
+  if (resources_.count(balloon_host))
+    return;
   NotificationResource* resource = new NotificationResource(balloon_host);
-  DCHECK(resources_.find(balloon_host) == resources_.end());
   resources_[balloon_host] = resource;
   task_manager_->AddResource(resource);
 }
 
 void NotificationResourceProvider::RemoveFromTaskManager(
     BalloonHost* balloon_host) {
   if (!updating_)
     return;
   std::map<BalloonHost*, NotificationResource*>::iterator iter =
       resources_.find(balloon_host);
   if (iter == resources_.end())
     return;
 
   // Remove the resource from the Task Manager.
   NotificationResource* resource = iter->second;
   task_manager_->RemoveResource(resource);
 
   // Remove it from the map.
   resources_.erase(iter);
 
   // Finally, delete the resource.
   delete resource;
 }
 
 }  // namespace task_manager