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
         // invalidation which would interfere with browser's processing content
         // frame. See crbug.com/394976.
         if (CommandLine.getInstance().hasSwitch(
                 ContentSwitches.RUNNING_PERFORMANCE_BENCHMARK)) {
             mTabObserver = new EmptyTabObserver();
         } else {
             mTabObserver = new TabObserverImpl();
         }
     }
 
     /**
      * The toolbar will visually represent the state of {@code tab}.
      * @param tab The Tab that should be represented.
      */
     public void showTab(ChromeShellTab tab) {
         if (mTab != null) mTab.removeObserver(mTabObserver);
 
+        mAddButton.setVisibility(GONE);

[Bernhard Bauer, 2014/11/04 12:22:10]

So, are we not going to show the stop/reload button again here?

In general, this seems a bit... random. What if there is some other code path
that hides or shows the tab switcher? If we want to have the invariant that the
add tab button is visible if and only if the tab switcher is visible, and the
stop/reload button is visible otherwise, we should see if there is a way to
observe state changes, instead of trying to hook into every single place where
we might hide or show the tab switcher.

[divya.bansal, 2014/11/05 09:04:22]

Done. Showing the add button when tabswitcher is shown.

+
         mTab = tab;
 
         if (mTab != null) {
             mTab.addObserver(mTabObserver);
             mUrlTextView.setText(mTab.getWebContents().getUrl());
         }
     }
 
     /**
      * Set the TabManager responsible for activating the tab switcher.
@@ skipping 24 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 43 matching lines @@
         mSuggestionPopup = new SuggestionPopup(getContext(), mUrlTextView, this);
         mUrlTextView.addTextChangedListener(mSuggestionPopup);
     }
 
     private void initializeTabSwitcherButton() {
         ImageButton tabSwitcherButton = (ImageButton) findViewById(R.id.tab_switcher);
         tabSwitcherButton.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View v) {
                 if (mTabManager != null) mTabManager.toggleTabSwitcher();
+                mAddButton.setVisibility(mTabManager.isTabSwitcherVisible() ? VISIBLE : GONE);
+                mStopReloadButton.setVisibility(mTabManager.isTabSwitcherVisible()
+                        ? GONE : VISIBLE);
             }
         });
     }
 
     private void initializeMenuButton() {
         ImageButton menuButton = (ImageButton) findViewById(R.id.menu_button);
         menuButton.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View view) {
                 if (mMenuHandler != null) mMenuHandler.showAppMenu(view, false, false);
@@ skipping 16 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();
+            }
+        });
+    }
+
     /**
      * @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);
         }
     }
 }