Remove redundant field initialization in Java code.

chrome/android/java/src/org/chromium/chrome/browser/physicalweb/PhysicalWebEnvironment.java

 // Copyright 2016 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.chrome.browser.physicalweb;
 
 import org.chromium.chrome.browser.ChromeApplication;
 
 /**
  * Tool that reports information about conflicting clients.
  */
 public class PhysicalWebEnvironment {
     private static final Object INSTANCE_LOCK = new Object();
-    private static PhysicalWebEnvironment sInstance = null;
+    private static PhysicalWebEnvironment sInstance;
 
     /**
      * Get a singleton instance of this class.
      * @param chromeApplication An instance of {@link ChromeApplication}, used to get the
      * appropriate PhysicalWebEnvironment implementation.
      * @return an instance of this class (or subclass) as decided by the application parameter
      */
     public static PhysicalWebEnvironment getInstance(ChromeApplication chromeApplication) {
         synchronized (INSTANCE_LOCK) {
             if (sInstance == null) {
                 sInstance = chromeApplication.createPhysicalWebEnvironment();
             }
         }
         return sInstance;
     }
 
     /**
      * Reports whether the environment has another notification-based Physical Web client enabled.
      * @return true if there is another notification-based Physical Web client enabled.
      */
     public boolean hasNotificationBasedClient() {
         return false;
     }
 }