[MediaNotification] Use common idiom to detect if OS version is "N"

chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java b/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
index 4526b71d4eb5502e3ee73aea7860a96c896dd015..3b6349be3d7d99e0e9dc7ba74ee7da038ca21e19 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
@@ -749,11 +749,6 @@ public class MediaNotificationManager {
 
     private boolean isRunningN() {
         // TODO(zqzhang): update this when N is released.
-        if (TextUtils.equals(Build.VERSION.CODENAME, "N")) return true;
-        if (TextUtils.equals(Build.VERSION.CODENAME, "REL")
-                && Build.VERSION.SDK_INT > Build.VERSION_CODES.M) {
-            return true;
-        }
-        return false;
+        return Build.VERSION.CODENAME.equals("N") || Build.VERSION.SDK_INT > Build.VERSION_CODES.M;
     }
 }