[Sync] Refactoring polling to be reliable.

chrome/browser/sync/glue/sync_backend_host_impl.cc

Index: chrome/browser/sync/glue/sync_backend_host_impl.cc
diff --git a/chrome/browser/sync/glue/sync_backend_host_impl.cc b/chrome/browser/sync/glue/sync_backend_host_impl.cc
index fa0ba02baa3b337efda2115451c2a6894b6bc7db..b84389c8fe64faa338bb32179f684e8ae36f4231 100644
--- a/chrome/browser/sync/glue/sync_backend_host_impl.cc
+++ b/chrome/browser/sync/glue/sync_backend_host_impl.cc
@@ -187,7 +187,7 @@ void SyncBackendHostImpl::StartSyncingWithServer() {
 
   registrar_->sync_thread()->message_loop()->PostTask(FROM_HERE,
       base::Bind(&SyncBackendHostCore::DoStartSyncing,
-                 core_.get(), routing_info));
+                 core_.get(), routing_info, sync_prefs_->GetLastPollTime()));
 }
 
 void SyncBackendHostImpl::SetEncryptionPassphrase(const std::string& passphrase,
@@ -719,6 +719,9 @@ void SyncBackendHostImpl::HandleSyncCycleCompletedOnFrontendLoop(
 
   SDVLOG(1) << "Got snapshot " << snapshot.ToString();
 
+  if (!snapshot.poll_finish_time().is_null())
+    sync_prefs_->SetLastPollTime(snapshot.poll_finish_time());
+
   // Process any changes to the datatypes we're syncing.
   // TODO(sync): add support for removing types.
   if (initialized())