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

components/sync/engine_impl/syncer_proto_util.cc

 // Copyright (c) 2012 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 "components/sync/engine_impl/syncer_proto_util.h"
 
 #include <map>
 
 #include "base/format_macros.h"
 #include "base/strings/stringprintf.h"
@@ skipping 454 matching lines @@
                    << "recent version.";
       return SERVER_RETURN_UNKNOWN_ERROR;
     case SYNC_SUCCESS:
       LogResponseProfilingData(*response);
       return SYNCER_OK;
     case THROTTLED:
       if (sync_protocol_error.error_data_types.Empty()) {
         DLOG(WARNING) << "Client fully throttled by syncer.";
         cycle->delegate()->OnThrottled(GetThrottleDelay(*response));
       } else {
+        // This is a special case, since server only throttle some of datatype,
+        // so can treat this case as partial failure.
         DLOG(WARNING) << "Some types throttled by syncer.";
         cycle->delegate()->OnTypesThrottled(
             sync_protocol_error.error_data_types, GetThrottleDelay(*response));
+        if (partial_failure_data_types != nullptr) {
+          *partial_failure_data_types = sync_protocol_error.error_data_types;
+        }
+        return SYNCER_OK;
       }
       return SERVER_RETURN_THROTTLED;
     case TRANSIENT_ERROR:
       return SERVER_RETURN_TRANSIENT_ERROR;
     case MIGRATION_DONE:
       LOG_IF(ERROR, 0 >= response->migrated_data_type_id_size())
           << "MIGRATION_DONE but no types specified.";
       cycle->delegate()->OnReceivedMigrationRequest(
           GetTypesToMigrate(*response));
       return SERVER_RETURN_MIGRATION_DONE;
     case CLEAR_PENDING:
       return SERVER_RETURN_CLEAR_PENDING;
     case NOT_MY_BIRTHDAY:
       return SERVER_RETURN_NOT_MY_BIRTHDAY;
     case DISABLED_BY_ADMIN:
       return SERVER_RETURN_DISABLED_BY_ADMIN;
     case PARTIAL_FAILURE:
-      // This only happens when partial throttling during GetUpdates.
+      // This only happens when partial backoff during GetUpdates.
       if (!sync_protocol_error.error_data_types.Empty()) {
-        DLOG(WARNING) << "Some types throttled by syncer during GetUpdates.";
-        cycle->delegate()->OnTypesThrottled(
-            sync_protocol_error.error_data_types, GetThrottleDelay(*response));
+        DLOG(WARNING)
+            << "Some types got partial failure by syncer during GetUpdates.";
+        cycle->delegate()->OnTypesBackedOff(
+            sync_protocol_error.error_data_types);
       }
       if (partial_failure_data_types != nullptr) {
         *partial_failure_data_types = sync_protocol_error.error_data_types;
       }
-      return SERVER_RETURN_PARTIAL_FAILURE;
+      return SYNCER_OK;
     case CLIENT_DATA_OBSOLETE:
       return SERVER_RETURN_CLIENT_DATA_OBSOLETE;
     default:
       NOTREACHED();
       return UNSET;
   }
 }
 
 // static
 bool SyncerProtoUtil::ShouldMaintainPosition(
@@ skipping 79 matching lines @@
 std::string SyncerProtoUtil::ClientToServerResponseDebugString(
     const ClientToServerResponse& response) {
   // Add more handlers as needed.
   std::string output;
   if (response.has_get_updates())
     output.append(GetUpdatesResponseString(response.get_updates()));
   return output;
 }
 
 }  // namespace syncer