Adding option for adding new tab in tab manager for chrome shell.

chrome/android/shell/java/src/org/chromium/chrome/shell/ChromeShellToolbar.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.chrome.shell;
 
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.content.res.Configuration;
 import android.graphics.drawable.ClipDrawable;
@@ skipping 55 matching lines @@
     private final TabObserver mTabObserver;
 
     private AppMenuHandler mMenuHandler;
     private AppMenuButtonHelper mAppMenuButtonHelper;
 
     private TabManager mTabManager;
 
     private SuggestionPopup mSuggestionPopup;
 
     private ImageButton mStopReloadButton;
+    private ImageButton mAddButton;
     private int mProgress = 0;
     private boolean mLoading = true;
 
     /**
      * @param context The Context the view is running in.
      * @param attrs   The attributes of the XML tag that is inflating the view.
      */
     public ChromeShellToolbar(Context context, AttributeSet attrs) {
         super(context, attrs);
         // When running performance benchmark, we don't want to observe the tab
@@ skipping 51 matching lines @@
 
     @Override
     protected void onFinishInflate() {
         super.onFinishInflate();
 
         mProgressDrawable = (ClipDrawable) findViewById(R.id.toolbar).getBackground();
         initializeUrlField();
         initializeTabSwitcherButton();
         initializeMenuButton();
         initializeStopReloadButton();
+        initializeAddButton();
     }
 
     void setMenuHandler(AppMenuHandler menuHandler) {
         mMenuHandler = menuHandler;
         ImageButton menuButton = (ImageButton) findViewById(R.id.menu_button);
         mAppMenuButtonHelper = new AppMenuButtonHelper(menuButton, mMenuHandler);
     }
 
     private void initializeUrlField() {
         mUrlTextView = (EditText) findViewById(R.id.url);
@@ skipping 83 matching lines @@
                 if (mTab == null) return;
                 if (mLoading) {
                     mTab.getWebContents().stop();
                 } else {
                     mTab.getWebContents().getNavigationController().reload(true);
                 }
             }
         });
     }
 
+    private void initializeAddButton() {
+        mAddButton = (ImageButton) findViewById(R.id.add_button);
+        mAddButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                mTabManager.createNewTab();
+            }
+        });
+    }
+
+    /**
+     * Shows the add button and hides the stop/reload button.

[Bernhard Bauer, 2014/11/12 10:00:13]

Technically, this can also do the opposite... Add ", or vice-versa" at the end?

[divya.bansal, 2014/11/12 10:18:04]

Done.

+     * @param visibility The visibility status of the tab switcher.

[Bernhard Bauer, 2014/11/12 10:00:13]

Replace "tab switcher" with "add button".

[divya.bansal, 2014/11/12 10:18:04]

Done.

+     */
+    public void showAddButton(boolean visibility) {
+        mAddButton.setVisibility(visibility ? VISIBLE : GONE);
+        mStopReloadButton.setVisibility(visibility ? GONE : VISIBLE);
+    }
+
     /**
      * @return Current tab that is shown by ChromeShell.
      */
     public ChromeShellTab getCurrentTab() {
         return mTab;
     }
 
     /**
      * Change the visibility of the software keyboard.
      * @param visible Whether the keyboard should be shown or hidden.
@@ skipping 19 matching lines @@
         public void onLoadProgressChanged(Tab tab, int progress) {
             if (tab == mTab) ChromeShellToolbar.this.onLoadProgressChanged(progress);
         }
 
         @Override
         public void onUpdateUrl(Tab tab, String url) {
             if (tab == mTab) ChromeShellToolbar.this.onUpdateUrl(url);
         }
     }
 }