Remove redundant field initialization in Java code.

chrome/android/java/src/org/chromium/chrome/browser/bookmarks/BookmarkDrawerListViewAdapter.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.bookmarks;
 
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseAdapter;
@@ skipping 18 matching lines @@
     static final int VIEW_TYPE_ITEM = 0;
     static final int VIEW_TYPE_DIVIDER = 1;
     static final int VIEW_TYPE_TITLE = 2;
 
     private BookmarkDelegate mDelegate;
     private List<Item> mTopSection = new ArrayList<Item>();
     private List<Item> mBottomSection = new ArrayList<Item>();
     // array containing the order of sections
     private List<?>[] mSections = {mTopSection, mBottomSection};
 
-    private BookmarkId mDesktopNodeId = null;
-    private BookmarkId mMobileNodeId = null;
-    private BookmarkId mOthersNodeId = null;
-    private List<BookmarkId> mManagedAndPartnerFolderIds = null;
+    private BookmarkId mDesktopNodeId;
+    private BookmarkId mMobileNodeId;
+    private BookmarkId mOthersNodeId;
+    private List<BookmarkId> mManagedAndPartnerFolderIds;
 
     /**
      * Represents each item in the list.
      */
     static class Item {
         final int mType;
         final BookmarkId mFolderId;
 
         Item(int itemType) {
             mType = itemType;
@@ skipping 260 matching lines @@
                 iconDrawableId = 0;
                 assert false;
         }
 
         listItemView.setText(title);
         listItemView.setIcon(iconDrawableId);
 
         return convertView;
     }
 }