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

Index: chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
diff --git a/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java b/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
index 36261cc03b48cde3361d813bbba1723c9ce3fe37..6be0839d8eca2c47ff60e6d445a385c81d749132 100644
--- a/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
+++ b/chrome/android/shell/java/src/org/chromium/chrome/shell/TabManager.java
@@ -56,7 +56,10 @@ public class TabManager extends LinearLayout {
 
         @Override
         public void willCloseTab(Tab tab, boolean animate) {
-            if (tab == mCurrentTab) setCurrentTab(null);
+            if (tab == mCurrentTab) {
+                setCurrentTab(null);
+                ensureTabExists();
+            }
         }
     };
 
@@ -125,7 +128,7 @@ public class TabManager extends LinearLayout {
      * 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();
         }
     }