Added a UI for the Interests Prototype.

chrome/android/java/src/org/chromium/chrome/browser/ntp/NewTabPageToolbar.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.ntp;
 
 import android.content.Context;
 import android.util.AttributeSet;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.LinearLayout;
 import android.widget.TextView;
 
 import org.chromium.base.ApiCompatibilityUtils;
 import org.chromium.chrome.R;
 import org.chromium.chrome.browser.offlinepages.OfflinePageBridge;
 import org.chromium.chrome.browser.widget.TintedDrawable;
 
 /**
  * The toolbar at the bottom of the new tab page. Contains buttons to open the bookmarks and
  * recent tabs pages.
  */
 public class NewTabPageToolbar extends LinearLayout {
 
-    private ViewGroup mBookmarksButton, mRecentTabsButton;
+    private ViewGroup mBookmarksButton, mRecentTabsButton, mInterestsButton;
 
     /**
      * Constructor for inflating from xml.
      */
     public NewTabPageToolbar(Context context, AttributeSet attrs) {
         super(context, attrs);
     }
 
     public View getBookmarksButton() {
         return mBookmarksButton;
     }
 
     public View getRecentTabsButton() {
         return mRecentTabsButton;
     }
 
+    public View getInterestsButton() {
+        return mInterestsButton;
+    }
+
     @Override
     protected void onFinishInflate() {
         mBookmarksButton = initButton(R.id.bookmarks_button, R.drawable.btn_star);
         mRecentTabsButton = initButton(R.id.recent_tabs_button, R.drawable.btn_recents);
         ((TextView) mBookmarksButton.getChildAt(0)).setText(OfflinePageBridge.isEnabled()
                 ? R.string.offline_pages_ntp_button_name : R.string.ntp_bookmarks);
+        mInterestsButton =  initButton(R.id.interests_button, R.drawable.btn_star_filled);
     }
 
     private ViewGroup initButton(int buttonId, int drawableId) {
         ViewGroup button = (ViewGroup) findViewById(buttonId);
         TextView textView = (TextView) button.getChildAt(0);
 
         TintedDrawable icon = TintedDrawable.constructTintedDrawable(getResources(), drawableId);
         ApiCompatibilityUtils.setCompoundDrawablesRelativeWithIntrinsicBounds(
                 textView, icon, null, null, null);
 
         return button;
     }
 }