[sync] Componentize sync: Part 2: Add SYNC_EXPORTs to files in src/sync/

sync/protocol/proto_enum_conversions.h

Index: sync/protocol/proto_enum_conversions.h
diff --git a/sync/protocol/proto_enum_conversions.h b/sync/protocol/proto_enum_conversions.h
index e3f9315734c507d289d30b2a98f23af610531e52..81b86f8535c73518b35f8ee7bfbfba7cd40fc5a8 100644
--- a/sync/protocol/proto_enum_conversions.h
+++ b/sync/protocol/proto_enum_conversions.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Copyright 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.
 
@@ -7,6 +7,7 @@
 
 // Keep this file in sync with the .proto files in this directory.
 
+#include "sync/base/sync_export.h"
 #include "sync/protocol/client_debug_info.pb.h"
 #include "sync/protocol/session_specifics.pb.h"
 #include "sync/protocol/sync.pb.h"
@@ -29,7 +30,7 @@ const char* GetPageTransitionRedirectTypeString(
     sync_pb::SyncEnums::PageTransitionRedirectType
         redirect_type);
 
-const char* GetUpdatesSourceString(
+SYNC_EXPORT const char* GetUpdatesSourceString(
     sync_pb::GetUpdatesCallerInfo::GetUpdatesSource updates_source);
 
 const char* GetResponseTypeString(