Remove redundant field initialization in Java code.

content/public/android/java/src/org/chromium/content/browser/BackgroundSyncNetworkObserver.java

 // Copyright 2015 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.
 
 package org.chromium.content.browser;
 
 import android.Manifest;
 import android.content.Context;
 import android.content.pm.PackageManager;
 import android.os.Process;
@@ skipping 23 matching lines @@
  * This class lives on the main thread.
  */
 @JNINamespace("content")
 class BackgroundSyncNetworkObserver implements NetworkChangeNotifierAutoDetect.Observer {
     private static final String TAG = "cr_BgSyncNetObserver";
 
     private NetworkChangeNotifierAutoDetect mNotifier;
     private Context mContext;
 
     // The singleton instance.
-    private static BackgroundSyncNetworkObserver sInstance = null;
+    private static BackgroundSyncNetworkObserver sInstance;
 
     // List of native observers. These are each called when the network state changes.
     private List<Long> mNativePtrs;
 
     private BackgroundSyncNetworkObserver(Context ctx) {
         ThreadUtils.assertOnUiThread();
         mContext = ctx;
         mNativePtrs = new ArrayList<Long>();
     }
 
@@ skipping 60 matching lines @@
     @Override
     public void onNetworkSoonToDisconnect(long netId) {}
     @Override
     public void onNetworkDisconnect(long netId) {}
     @Override
     public void purgeActiveNetworkList(long[] activeNetIds) {}
 
     @NativeClassQualifiedName("BackgroundSyncNetworkObserverAndroid::Observer")
     private native void nativeNotifyConnectionTypeChanged(long nativePtr, int newConnectionType);
 }