[Sync] Move snapshot cache from SBHI to PSS.

components/browser_sync/profile_sync_service.cc

Index: components/browser_sync/profile_sync_service.cc
diff --git a/components/browser_sync/profile_sync_service.cc b/components/browser_sync/profile_sync_service.cc
index c17718f64871c53878e870b9fa6bc8309f0fd5de..377c1e53aee9c2b2df9ad417a433beb28bafe893 100644
--- a/components/browser_sync/profile_sync_service.cc
+++ b/components/browser_sync/profile_sync_service.cc
@@ -1023,10 +1023,16 @@ void ProfileSyncService::OnEngineInitialized(
     RequestStart();
 }
 
-void ProfileSyncService::OnSyncCycleCompleted() {
+void ProfileSyncService::OnSyncCycleCompleted(
+    const syncer::SyncCycleSnapshot& snapshot) {
   DCHECK(thread_checker_.CalledOnValidThread());
+
+  last_snapshot_ = snapshot;
+
   UpdateLastSyncedTime();
-  const syncer::SyncCycleSnapshot snapshot = GetLastCycleSnapshot();
+  if (!snapshot.poll_finish_time().is_null())
+    sync_prefs_.SetLastPollTime(snapshot.poll_finish_time());
+
   if (IsDataTypeControllerRunning(syncer::SESSIONS) &&
       snapshot.model_neutral_state().get_updates_request_types.Has(
           syncer::SESSIONS) &&
@@ -1866,9 +1872,7 @@ syncer::UserShare* ProfileSyncService::GetUserShare() const {
 
 syncer::SyncCycleSnapshot ProfileSyncService::GetLastCycleSnapshot() const {
   DCHECK(thread_checker_.CalledOnValidThread());
-  if (engine_)
-    return engine_->GetLastCycleSnapshot();
-  return syncer::SyncCycleSnapshot();
+  return last_snapshot_;

[pavely, 2017/01/12 00:27:13]

Previously if user signs out this method would return default snapshot. Now it
will return last snapshot. I guess there should be no harm in it.

[maxbogue, 2017/01/12 01:55:02]

Hmm... I'm going to clear it in ShutdownImpl just to be safe.

 }
 
 bool ProfileSyncService::HasUnsyncedItems() const {