Use DCHECKs when observing only a single notification.

chrome/browser/printing/print_view_manager_base.cc

 // Copyright 2013 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/printing/print_view_manager_base.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/auto_reset.h"
@@ skipping 222 matching lines @@
                         OnShowInvalidPrinterSettingsError)
     IPC_MESSAGE_UNHANDLED(handled = false)
   IPC_END_MESSAGE_MAP()
   return handled || PrintManager::OnMessageReceived(message);
 }
 
 void PrintViewManagerBase::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
-  switch (type) {
-    case chrome::NOTIFICATION_PRINT_JOB_EVENT: {
-      OnNotifyPrintJobEvent(*content::Details<JobEventDetails>(details).ptr());
-      break;
-    }
-    default: {
-      NOTREACHED();
-      break;
-    }
-  }
+  DCHECK_EQ(chrome::NOTIFICATION_PRINT_JOB_EVENT, type);
+  OnNotifyPrintJobEvent(*content::Details<JobEventDetails>(details).ptr());
 }
 
 void PrintViewManagerBase::OnNotifyPrintJobEvent(
     const JobEventDetails& event_details) {
   switch (event_details.type()) {
     case JobEventDetails::FAILED: {
       TerminatePrintJob(true);
 
       content::NotificationService::current()->Notify(
           chrome::NOTIFICATION_PRINT_JOB_RELEASED,
@@ skipping 265 matching lines @@
   scoped_refptr<PrinterQuery> printer_query;
   printer_query = queue_->PopPrinterQuery(cookie);
   if (!printer_query.get())
     return;
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&PrinterQuery::StopWorker, printer_query.get()));
 }
 
 }  // namespace printing