Remove redundant field initialization in Java code.

base/android/java/src/org/chromium/base/library_loader/Linker.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.base.library_loader;
 
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Parcel;
 import android.os.ParcelFileDescriptor;
@@ skipping 177 matching lines @@
     protected static final boolean DEBUG = false;
 
     // Used to pass the shared RELRO Bundle through Binder.
     public static final String EXTRA_LINKER_SHARED_RELROS =
             "org.chromium.base.android.linker.shared_relros";
 
     // Guards all access to the linker.
     protected final Object mLock = new Object();
 
     // The name of a class that implements TestRunner.
-    private String mTestRunnerClassName = null;
+    private String mTestRunnerClassName;
 
     // Size of reserved Breakpad guard region. Should match the value of
     // kBreakpadGuardRegionBytes on the JNI side. Used when computing the load
     // addresses of multiple loaded libraries. Set to 0 to disable the guard.
     protected static final int BREAKPAD_GUARD_REGION_BYTES = 16 * 1024 * 1024;
 
     // Size of the area requested when using ASLR to obtain a random load address.
     // Should match the value of kAddressSpaceReservationSize on the JNI side.
     // Used when computing the load addresses of multiple loaded libraries to
     // ensure that we don't try to load outside the area originally requested.
     protected static final int ADDRESS_SPACE_RESERVATION = 192 * 1024 * 1024;
 
     // Constants used to indicate a given Linker implementation, for testing.
     //   LEGACY       -> Always uses the LegacyLinker implementation.
     //   MODERN       -> Always uses the ModernLinker implementation.
     // NOTE: These names are known and expected by the Linker test scripts.
     public static final int LINKER_IMPLEMENTATION_LEGACY = 1;
     public static final int LINKER_IMPLEMENTATION_MODERN = 2;
 
     // Singleton.
-    private static Linker sSingleton = null;
+    private static Linker sSingleton;
     private static Object sSingletonLock = new Object();
 
     // Protected singleton constructor.
     protected Linker() { }
 
     /**
      * Get singleton instance. Returns either a LegacyLinker or a ModernLinker.
      *
      * Returns a ModernLinker if running on Android M or later, otherwise returns
      * a LegacyLinker.
@@ skipping 586 matching lines @@
      * Return a random address that should be free to be mapped with the given size.
      * Maps an area large enough for the largest library we might attempt to load,
      * and if successful then unmaps it and returns the address of the area allocated
      * by the system (with ASLR). The idea is that this area should remain free of
      * other mappings until we map our library into it.
      *
      * @return address to pass to future mmap, or 0 on error.
      */
     private static native long nativeGetRandomBaseLoadAddress();
 }