[Sync] Convert sync to a static library.

components/sync/core/network_resources.h

 // Copyright 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.
 
 #ifndef COMPONENTS_SYNC_CORE_NETWORK_RESOURCES_H_
 #define COMPONENTS_SYNC_CORE_NETWORK_RESOURCES_H_
 
 #include <memory>
 
-#include "components/sync/base/sync_export.h"
 #include "components/sync/core/network_time_update_callback.h"
 
 namespace net {
 class URLRequestContextGetter;
 }  // namespace net
 
 namespace syncer {
 
 class CancelationSignal;
 class HttpPostProviderFactory;
 
-class SYNC_EXPORT NetworkResources {
+class NetworkResources {
  public:
   virtual ~NetworkResources() {}
 
   virtual std::unique_ptr<HttpPostProviderFactory> GetHttpPostProviderFactory(
       const scoped_refptr<net::URLRequestContextGetter>&
           baseline_context_getter,
       const NetworkTimeUpdateCallback& network_time_update_callback,
       CancelationSignal* cancelation_signal) = 0;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_CORE_NETWORK_RESOURCES_H_