Remove redundant field initialization in Java code.

content/public/android/java/src/org/chromium/content_public/browser/InterfaceRegistrar.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.content_public.browser;
 
 import android.content.Context;
 
 import org.chromium.services.service_manager.InterfaceRegistry;
 
 import java.util.ArrayList;
 import java.util.List;
 
 /**
  * A registrar for mojo interface implementations to provide to an InterfaceRegistry.
  *
  * @param <ParamType> the type of parameter to pass to the InterfaceRegistrar when adding its
  *     interfaces to an InterfaceRegistry
  */
 public interface InterfaceRegistrar<ParamType> {
     /** Invoked to register interfaces on |registry|, parametrized by |paramValue|. */
     public void registerInterfaces(InterfaceRegistry registry, ParamType paramValue);
 
     /** A registry of InterfaceRegistrars. */
     public static class Registry<ParamType> {
-        private static Registry<Context> sContextRegistry = null;
-        private static Registry<WebContents> sWebContentsRegistry = null;
+        private static Registry<Context> sContextRegistry;
+        private static Registry<WebContents> sWebContentsRegistry;
 
         private List<InterfaceRegistrar<ParamType>> mRegistrars =
                 new ArrayList<InterfaceRegistrar<ParamType>>();
 
         public static void applyContextRegistrars(
                 InterfaceRegistry interfaceRegistry, Context context) {
             if (sContextRegistry == null) {
                 return;
             }
             sContextRegistry.applyRegistrars(interfaceRegistry, context);
@@ skipping 27 matching lines @@
             mRegistrars.add(registrar);
         }
 
         private void applyRegistrars(InterfaceRegistry interfaceRegistry, ParamType param) {
             for (InterfaceRegistrar<ParamType> registrar : mRegistrars) {
                 registrar.registerInterfaces(interfaceRegistry, param);
             }
         }
     }
 }