Use DCHECKs when observing only a single notification.

chrome/browser/prerender/prerender_manager.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/prerender/prerender_manager.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <functional>
@@ skipping 1185 matching lines @@
 void PrerenderManager::RecordFinalStatusWithoutCreatingPrerenderContents(
     const GURL& url, Origin origin, FinalStatus final_status) const {
   PrerenderHistory::Entry entry(url, final_status, origin, base::Time::Now());
   prerender_history_->AddEntry(entry);
   histograms_->RecordFinalStatus(origin, final_status);
 }
 
 void PrerenderManager::Observe(int type,
                                const content::NotificationSource& source,
                                const content::NotificationDetails& details) {
-  switch (type) {
-    case chrome::NOTIFICATION_PROFILE_DESTROYED:
-      DestroyAllContents(FINAL_STATUS_PROFILE_DESTROYED);
-      on_close_web_contents_deleters_.clear();
-      break;
-    default:
-      NOTREACHED() << "Unexpected notification sent.";
-      break;
-  }
+  DCHECK_EQ(chrome::NOTIFICATION_PROFILE_DESTROYED, type);
+
+  DestroyAllContents(FINAL_STATUS_PROFILE_DESTROYED);
+  on_close_web_contents_deleters_.clear();
 }
 
 void PrerenderManager::OnCreatingAudioStream(int render_process_id,
                                              int render_frame_id) {
   content::RenderFrameHost* render_frame_host =
       content::RenderFrameHost::FromID(render_process_id, render_frame_id);
   WebContents* tab = WebContents::FromRenderFrameHost(render_frame_host);
   if (!tab)
     return;
 
@@ skipping 78 matching lines @@
 }
 
 void PrerenderManager::RenderProcessHostDestroyed(
     content::RenderProcessHost* host) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   size_t erased = prerender_process_hosts_.erase(host);
   DCHECK_EQ(1u, erased);
 }
 
 }  // namespace prerender