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 54 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 150 matching lines @@
                 if (mTab == null) return;
                 if (mLoading) {
                     mTab.getWebContents().stop();
                 } else {
                     mTab.getWebContents().getNavigationController().reload(true);
                 }
             }
         });
     }
 
+
+    public void initializeAddButton(boolean tabswitcher) {

[Bernhard Bauer, 2014/11/05 10:01:53]

This should have a Javadoc comment. Also, |tabswitcher| as a boolean parameter
isn't very intuitive: what does a true or false value actually mean?

And finally, there is no need to reinitialize |mAddButton| or set a new
OnClickListener every time we want to hide or show the button.

+        mAddButton = (ImageButton) findViewById(R.id.add_button);
+        mAddButton.setVisibility(tabswitcher ? VISIBLE : GONE);
+        mStopReloadButton.setVisibility(tabswitcher ? GONE : VISIBLE);
+        mAddButton.setOnClickListener(new OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                mTabManager.createNewTab();
+            }
+        });
+    }
+
+
     /**
      * @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);
         }
     }
 }