Remove redundant field initialization in Java code.

chrome/android/java/src/org/chromium/chrome/browser/customtabs/RequestThrottler.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.chrome.browser.customtabs;
 
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.os.AsyncTask;
@@ skipping 28 matching lines @@
     private static final float MAX_SCORE = 10;
     // TODO(lizeb): Control this value using Finch.
     private static final long BAN_DURATION_MS = TimeUnit.DAYS.toMillis(7);
     private static final long FORGET_AFTER_MS = TimeUnit.DAYS.toMillis(14);
     private static final float ALPHA = MAX_SCORE / BAN_DURATION_MS;
     private static final String PREFERENCES_NAME = "customtabs_client_bans";
     private static final String SCORE = "score_";
     private static final String LAST_REQUEST = "last_request_";
     private static final String BANNED_UNTIL = "banned_until_";
 
-    private static SparseArray<RequestThrottler> sUidToThrottler = null;
+    private static SparseArray<RequestThrottler> sUidToThrottler;
 
     private final SharedPreferences mSharedPreferences;
     private final int mUid;
     private float mScore;
     private long mLastPrerenderRequestMs;
     private long mBannedUntilMs;
-    private String mUrl = null;
+    private String mUrl;
 
     /**
      * Updates the prediction stats and returns whether prediction is allowed.
      *
      * The policy is:
      * 1. If the client does not wait more than mDelayMs, decline the request.
      * 2. If the client waits for more than mDelayMs but less than 2*mDelayMs, accept the request
      *    and double mDelayMs.
      * 3. If the client waits for more than 2*mDelayMs, accept the request and reset mDelayMs.
      *
@@ skipping 165 matching lines @@
         editor.apply();
     }
 
     @VisibleForTesting
     static void purgeAllEntriesForTesting(Context context) {
         SharedPreferences sharedPreferences = context.getSharedPreferences(PREFERENCES_NAME, 0);
         sharedPreferences.edit().clear().apply();
         if (sUidToThrottler != null) sUidToThrottler.clear();
     }
 }