[Sync] Sync client should to exponential backoff when receive partial failure

components/sync/engine_impl/cycle/test_util.h

Index: components/sync/engine_impl/cycle/test_util.h
diff --git a/components/sync/engine_impl/cycle/test_util.h b/components/sync/engine_impl/cycle/test_util.h
index cd49a66cfa9a1b7f8b6681bf683c6ddf2a0042d6..ece69060f0af5a5175d4cbfd6d9f5d37bc584139 100644
--- a/components/sync/engine_impl/cycle/test_util.h
+++ b/components/sync/engine_impl/cycle/test_util.h
@@ -59,6 +59,8 @@ void SimulateTypesThrottledImpl(SyncCycle* cycle,
                                 ModelTypeSet types,
                                 const base::TimeDelta& delta);
 
+void SimulatePartialFailureImpl(SyncCycle* cycle, ModelTypeSet types);
+
 // Works with poll cycles.
 void SimulatePollIntervalUpdateImpl(ModelTypeSet requested_types,
                                     SyncCycle* cycle,
@@ -78,6 +80,10 @@ ACTION_P2(SimulateTypesThrottled, types, throttle) {
   SimulateTypesThrottledImpl(arg0, types, throttle);
 }
 
+ACTION_P(SimulatePartialFailure, types) {
+  SimulatePartialFailureImpl(arg0, types);
+}
+
 ACTION_P(SimulatePollIntervalUpdate, poll) {
   SimulatePollIntervalUpdateImpl(arg0, arg1, poll);
 }