Use DCHECKs when observing only a single notification.

chrome/browser/task_manager/web_contents_information.cc

 // Copyright 2014 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/web_contents_information.h"
 #include "content/public/browser/notification_service.h"
 #include "content/public/browser/notification_types.h"
 
 namespace task_manager {
 
@@ skipping 20 matching lines @@
       this,
       content::NOTIFICATION_WEB_CONTENTS_CONNECTED,
       content::NotificationService::AllBrowserContextsAndSources());
   observer_callback_.Reset();
 }
 
 void NotificationObservingWebContentsInformation::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
+  DCHECK_EQ(content::NOTIFICATION_WEB_CONTENTS_CONNECTED, type);
+
   content::WebContents* web_contents =
       content::Source<content::WebContents>(source).ptr();
-
-  switch (type) {
-    case content::NOTIFICATION_WEB_CONTENTS_CONNECTED:
-      if (CheckOwnership(web_contents))
-        observer_callback_.Run(web_contents);
-      break;
-  }
+  if (CheckOwnership(web_contents))
+    observer_callback_.Run(web_contents);
 }
 
 }  // namespace task_manager