Opening new "about:blank" tab if all tabs are closed in tab switcher mode.

chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.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.content.Context;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
 import android.view.View;
@@ skipping 38 matching lines @@
     private final EmptyTabModelObserver mTabModelObserver = new EmptyTabModelObserver() {
         @Override
         public void didSelectTab(Tab tab, TabSelectionType type, int lastId) {
             assert tab instanceof ChromeShellTab;
             setCurrentTab((ChromeShellTab) tab);
             hideTabSwitcher();
         }
 
         @Override
         public void willCloseTab(Tab tab, boolean animate) {
-            if (tab == mCurrentTab) setCurrentTab(null);
+            if (tab == mCurrentTab) {
+                setCurrentTab(null);
+                ensureTabExists();
+            }
         }
     };
 
     /**
      * @param context The Context the view is running in.
      * @param attrs   The attributes of the XML tag that is inflating the view.
      */
     public TabManager(Context context, AttributeSet attrs) {
         super(context, attrs);
     }
@@ skipping 48 matching lines @@
      * @return The currently visible {@link ChromeShellTab}.
      */
     public ChromeShellTab getCurrentTab() {
         return mCurrentTab;
     }
 
     /**
      * Ensures that at least one tab exists, by opening a new one if necessary.
      */
     public void ensureTabExists() {
-        if (mTabModelSelector.getCurrentModel().getCount() == 0) {
+        if (mTabModelSelector.getCurrentModel().getCount() == 1) {

[Bernhard Bauer, 2014/11/19 12:13:40]

This also changes the semantics of existing code. This method is currently
called at startup to ensure that at least one tab exists. Now, if there is no
tab open, it won't open a new one, and if there is a tab open, it will open
another one.

[divya.bansal, 2014/11/19 12:25:49]

Yes thats true, actually in tabmodelbase.java getcount gives size of |tabs|
arraylist and willCloseTab() is called before removing tab in the arraylist. So
if we want to check for count =0, then after removing only we can check and
create new tab.
That is why , I was calling didclosetab after removing tab. didclosetab() is
also member of tabmodelobserver and that too need to be handled.

[Bernhard Bauer, 2014/11/19 12:54:39]

I already told you what to do: in willCloseTab() (i.e. right before the tab is
closed), call createNewTab() if there is exactly one tab (because that means
that we are about to close the last tab).

[divya.bansal, 2014/11/19 14:48:39]

Done.

             createNewTab();
         }
     }
 
     /**
      * Opens a new blank tab.
      */
     public void createNewTab() {
         createTab("about:blank", TabLaunchType.FROM_MENU_OR_OVERVIEW);
     }
@@ skipping 110 matching lines @@
         LoadUrlParams loadUrlParams = new LoadUrlParams(url);
         loadUrlParams.setTransitionType(PageTransition.TYPED | PageTransition.FROM_ADDRESS_BAR);
         Tab tab = mTabModelSelector.getCurrentTab();
         if (tab != null) {
             tab.loadUrl(loadUrlParams);
             return tab;
         }
         return createTab(url, TabLaunchType.FROM_KEYBOARD);
     }
 }