Remove redundant field initialization in Java code.

ui/android/java/src/org/chromium/ui/base/DeviceFormFactor.java

 // Copyright 2014 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.ui.base;
 
 import android.content.Context;
 import android.os.Build;
 import android.util.DisplayMetrics;
 import android.view.WindowManager;
 
 import org.chromium.base.annotations.CalledByNative;
 
 /**
  * UI utilities for accessing form factor information.
  */
 public class DeviceFormFactor {
 
     /**
      * The minimum width that would classify the device as a tablet or a large tablet.
      */
     public static final int MINIMUM_TABLET_WIDTH_DP = 600;
     private static final int MINIMUM_LARGE_TABLET_WIDTH_DP = 720;
 
-    private static Boolean sIsTablet = null;
-    private static Boolean sIsLargeTablet = null;
-    private static Integer sMinimumTabletWidthPx = null;
-    private static Float sDensity = null;
+    private static Boolean sIsTablet;
+    private static Boolean sIsLargeTablet;
+    private static Integer sMinimumTabletWidthPx;
+    private static Float sDensity;
 
     /**
      * @param context {@link Context} used to get the Application Context.
      * @return Whether the app should treat the device as a tablet for layout. This method is not
      *         affected by Android N multi-window.
      */
     @CalledByNative
     public static boolean isTablet(Context context) {
         if (sIsTablet == null) {
             sIsTablet = getSmallestDeviceWidthDp(context) >= MINIMUM_TABLET_WIDTH_DP;
@@ skipping 71 matching lines @@
      * Sets whether the device is a tablet.
      * @param isTablet Whether the app should treat the device as a tablet for layout.
      * @param isLargeTablet Whether the app should treat the device as a large tablet for layout.
      *                      If this is true, isTablet should also be true.
      */
     public static void setIsTablet(boolean isTablet, boolean isLargeTablet) {
         sIsTablet = isTablet;
         sIsLargeTablet = isLargeTablet;
     }
 }