Add a new SyncedTabDelegate for Android.

chrome/browser/sync/glue/session_model_associator.cc

Index: chrome/browser/sync/glue/session_model_associator.cc
diff --git a/chrome/browser/sync/glue/session_model_associator.cc b/chrome/browser/sync/glue/session_model_associator.cc
index 798db3a965c303ad16c5cbc22b4db6e9e4e55d31..269d12c778547aa7162e260c0fe5ed1625830afc 100644
--- a/chrome/browser/sync/glue/session_model_associator.cc
+++ b/chrome/browser/sync/glue/session_model_associator.cc
@@ -237,10 +237,10 @@ bool SessionModelAssociator::AssociateWindows(bool reload_tabs,
 
         if (reload_tabs) {
           SyncedTabDelegate* tab = (*i)->GetTabAt(j);
-          // It's possible for GetTabAt to return a null tab if it's not in
-          // memory. We can assume this means the tab already existed but hasn't
-          // changed, so no need to reassociate.
-          if (tab && !AssociateTab(*tab, error)) {
+          // It's possible for GetTabAt to return a null tab or a tab which has
+          // no web contents. We can assume this means the tab already existed
+          // but hasn't changed, so no need to reassociate.
+          if (tab && tab->HasWebContents() && !AssociateTab(*tab, error)) {

[Yaron, 2013/05/21 18:32:07]

I believe the existence-check for tab was purely for the webcontents-less case
on Android. Can't we always ensure that we have a tab now? 

[shashi, 2013/05/21 23:11:21]

Done.

             // Association failed. Either we need to re-associate, or this is an
             // unrecoverable error.
             return false;