Use DCHECKs when observing only a single notification.

chrome/browser/printing/print_job.cc

Index: chrome/browser/printing/print_job.cc
diff --git a/chrome/browser/printing/print_job.cc b/chrome/browser/printing/print_job.cc
index 0a6ddf8a79256b4f8685d0a6cd8eddea0d734b52..a9ef39783902d99c4ce6588bc88b2414daa619b5 100644
--- a/chrome/browser/printing/print_job.cc
+++ b/chrome/browser/printing/print_job.cc
@@ -92,15 +92,9 @@ void PrintJob::Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) {
   DCHECK(RunsTasksOnCurrentThread());
-  switch (type) {
-    case chrome::NOTIFICATION_PRINT_JOB_EVENT: {
-      OnNotifyPrintJobEvent(*content::Details<JobEventDetails>(details).ptr());
-      break;
-    }
-    default: {
-      break;
-    }
-  }
+  DCHECK_EQ(chrome::NOTIFICATION_PRINT_JOB_EVENT, type);
+
+  OnNotifyPrintJobEvent(*content::Details<JobEventDetails>(details).ptr());
 }
 
 void PrintJob::GetSettingsDone(const PrintSettings& new_settings,