Use DCHECKs when observing only a single notification.

chrome/browser/renderer_context_menu/render_view_context_menu_browsertest_util.cc

Index: chrome/browser/renderer_context_menu/render_view_context_menu_browsertest_util.cc
diff --git a/chrome/browser/renderer_context_menu/render_view_context_menu_browsertest_util.cc b/chrome/browser/renderer_context_menu/render_view_context_menu_browsertest_util.cc
index ca8e7884c8e4d55556de5fa15b47829386ece095..8548f9c2af4cb7f9db4f77257ac1eee39a2b6980 100644
--- a/chrome/browser/renderer_context_menu/render_view_context_menu_browsertest_util.cc
+++ b/chrome/browser/renderer_context_menu/render_view_context_menu_browsertest_util.cc
@@ -29,20 +29,13 @@ void ContextMenuNotificationObserver::Observe(
     int type,
     const content::NotificationSource& source,
     const content::NotificationDetails& details) {
-  switch (type) {
-    case chrome::NOTIFICATION_RENDER_VIEW_CONTEXT_MENU_SHOWN: {
-      RenderViewContextMenu* context_menu =
-          content::Source<RenderViewContextMenu>(source).ptr();
-      base::ThreadTaskRunnerHandle::Get()->PostTask(
-          FROM_HERE,
-          base::Bind(&ContextMenuNotificationObserver::ExecuteCommand,
-                     base::Unretained(this), context_menu));
-      break;
-    }
+  DCHECK_EQ(chrome::NOTIFICATION_RENDER_VIEW_CONTEXT_MENU_SHOWN, type);
 
-    default:
-      NOTREACHED();
-  }
+  RenderViewContextMenu* context_menu =
+      content::Source<RenderViewContextMenu>(source).ptr();
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&ContextMenuNotificationObserver::ExecuteCommand,
+                            base::Unretained(this), context_menu));
 }
 
 void ContextMenuNotificationObserver::ExecuteCommand(