Remove redundant field initialization in Java code.

chrome/android/java/src/org/chromium/chrome/browser/media/router/cast/CastSessionInfo.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.media.router.cast;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
@@ skipping 11 matching lines @@
         public final double level;
         /**
          * Whether the receiver is muted.
          */
         public final boolean muted;
 
         /**
          * Use this class to construct an instance of {@link VolumeInfo}.
          */
         public static class Builder {
-            private double mLevel = 0;
-            private boolean mMuted = false;
+            private double mLevel;
+            private boolean mMuted;
 
             public Builder setLevel(double level) {
                 mLevel = level;
                 return this;
             }
 
             public Builder setMuted(boolean muted) {
                 mMuted = muted;
                 return this;
             }
@@ skipping 48 matching lines @@
          */
         public final String receiverType;
 
         /**
          * Use this class to create an instance of {@link ReceiverInfo}.
          */
         public static class Builder {
             private String mLabel = "";
             private String mFriendlyName = "";
             private List<String> mCapabilities = new ArrayList<String>();
-            private VolumeInfo mVolume = null;
-            private int mIsActiveInput = 0;
+            private VolumeInfo mVolume;
+            private int mIsActiveInput;
             private String mDisplayStatus = "";
             private String mReceiverType = "";
 
             public Builder setLabel(String label) {
                 mLabel = label;
                 return this;
             }
 
             public Builder setFriendlyName(String friendlyName) {
                 mFriendlyName = friendlyName;
@@ skipping 102 matching lines @@
      * The display name of the {@link CastSession}.
      */
     public final String displayName;
 
     /**
      * Use this class to create an instance of {@link CastSessionInfo}.
      */
     public static class Builder {
         private String mSessionId = "";
         private String mStatusText = "";
-        private ReceiverInfo mReceiver = null;
+        private ReceiverInfo mReceiver;
         private List<String> mNamespaces = new ArrayList<String>();
         private List<String> mMedia = new ArrayList<String>();
         private String mStatus = "";
         private String mTransportId = "";
         private String mAppId = "";
         private String mDisplayName = "";
 
         public Builder setSessionId(String sessionId) {
             mSessionId = sessionId;
             return this;
@@ skipping 78 matching lines @@
         this.statusText = statusText;
         this.receiver = receiver;
         this.namespaces = namespaces;
         this.media = media;
         this.status = status;
         this.transportId = transportId;
         this.appId = appId;
         this.displayName = displayName;
     }
 }