Log the sync communication that happens between client and server.

chrome/browser/sync/protocol/proto_enum_conversions.h

 // 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.
 
 #ifndef CHROME_BROWSER_SYNC_PROTOCOL_PROTO_ENUM_CONVERSIONS_H_
 #define CHROME_BROWSER_SYNC_PROTOCOL_PROTO_ENUM_CONVERSIONS_H_
 #pragma once
 
 // Keep this file in sync with the .proto files in this directory.
 
@@ skipping 14 matching lines @@
 const char* GetPageTransitionString(
     sync_pb::TabNavigation::PageTransition page_transition);
 
 const char* GetPageTransitionQualifierString(
     sync_pb::TabNavigation::PageTransitionQualifier
         page_transition_qualifier);
 
 const char* GetUpdatesSourceString(
     sync_pb::GetUpdatesCallerInfo::GetUpdatesSource updates_source);
 
+const char* GetResponseTypeString(
+    sync_pb::CommitResponse::ResponseType response_type);
+
+const char* GetErrorTypeString(sync_pb::SyncEnums::ErrorType error_type);
+
+const char* GetActionString(
+   sync_pb::ClientToServerResponse::Error::Action action);
+
 const char* GetDeviceTypeString(
     sync_pb::SessionHeader::DeviceType device_type);
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_PROTOCOL_PROTO_ENUM_CONVERSIONS_H_