Use DCHECKs when observing only a single notification.

chrome/browser/chromeos/app_mode/startup_app_launcher.cc

Index: chrome/browser/chromeos/app_mode/startup_app_launcher.cc
diff --git a/chrome/browser/chromeos/app_mode/startup_app_launcher.cc b/chrome/browser/chromeos/app_mode/startup_app_launcher.cc
index 675c09d4f73d900b8c3c58ad9add6e152bef631c..fa1ee128154b3f0f48d224a899137eb5625e3fba 100644
--- a/chrome/browser/chromeos/app_mode/startup_app_launcher.cc
+++ b/chrome/browser/chromeos/app_mode/startup_app_launcher.cc
@@ -311,12 +311,12 @@ void StartupAppLauncher::OnExtensionUpdateCheckFinished() {
 void StartupAppLauncher::Observe(int type,
                                  const content::NotificationSource& source,
                                  const content::NotificationDetails& details) {
-  DCHECK(type == extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND);
-  typedef const std::pair<std::string, Version> UpdateDetails;
+  DCHECK_EQ(extensions::NOTIFICATION_EXTENSION_UPDATE_FOUND, type);
+  using UpdateDetails = const std::pair<std::string, Version>;
   const std::string& id = content::Details<UpdateDetails>(details)->first;
   const Version& version = content::Details<UpdateDetails>(details)->second;
   VLOG(1) << "Found extension update id=" << id
-      << " version=" << version.GetString();
+          << " version=" << version.GetString();
   extension_update_found_ = true;
 }