sync: Add pre-commit update avoidance mode + flag

sync/sessions/nudge_tracker.cc

 // Copyright (c) 2013 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.
 
 #include "sync/sessions/nudge_tracker.h"
 
 #include "base/basictypes.h"
 #include "sync/internal_api/public/base/invalidation.h"
 #include "sync/internal_api/public/sessions/sync_source_info.h"
 #include "sync/protocol/sync.pb.h"
@@ skipping 20 matching lines @@
 bool NudgeTracker::IsSyncRequired() const {
   for (TypeTrackerMap::const_iterator it = type_trackers_.begin();
        it != type_trackers_.end(); ++it) {
     if (it->second.IsSyncRequired()) {
       return true;
     }
   }
   return false;
 }
 
+bool NudgeTracker::IsGetUpdatesRequired() const {
+  for (TypeTrackerMap::const_iterator it = type_trackers_.begin();
+       it != type_trackers_.end(); ++it) {
+    if (it->second.IsGetUpdatesRequired()) {
+      return true;
+    }
+  }
+  return false;
+}
+
 void NudgeTracker::RecordSuccessfulSyncCycle() {
   updates_source_ = sync_pb::GetUpdatesCallerInfo::UNKNOWN;
 
   // A successful cycle while invalidations are enabled puts us back into sync.
   invalidations_out_of_sync_ = !invalidations_enabled_;
 
   for (TypeTrackerMap::iterator it = type_trackers_.begin();
        it != type_trackers_.end(); ++it) {
     it->second.RecordSuccessfulSyncCycle();
   }
@@ skipping 170 matching lines @@
 
 void NudgeTracker::SetHintBufferSize(size_t size) {
   for (TypeTrackerMap::iterator it = type_trackers_.begin();
        it != type_trackers_.end(); ++it) {
     it->second.UpdatePayloadBufferSize(size);
   }
 }
 
 }  // namespace sessions
 }  // namespace syncer