[Sync] Convert sync to a static library.

components/sync/syncable/syncable_write_transaction.h

Index: components/sync/syncable/syncable_write_transaction.h
diff --git a/components/sync/syncable/syncable_write_transaction.h b/components/sync/syncable/syncable_write_transaction.h
index 05a2fe5283e5004812eefe0dd01485e2d1bbcd5c..57135a6254c6ca594bbdf0d047f22fcdc2f5da33 100644
--- a/components/sync/syncable/syncable_write_transaction.h
+++ b/components/sync/syncable/syncable_write_transaction.h
@@ -10,17 +10,16 @@
 #include <vector>
 
 #include "base/macros.h"
-#include "components/sync/base/sync_export.h"
 #include "components/sync/syncable/entry_kernel.h"
 #include "components/sync/syncable/syncable_base_write_transaction.h"
 
 namespace syncer {
 namespace syncable {
 
-SYNC_EXPORT extern const int64_t kInvalidTransactionVersion;
+extern const int64_t kInvalidTransactionVersion;
 
 // Locks db in constructor, unlocks in destructor.
-class SYNC_EXPORT WriteTransaction : public BaseWriteTransaction {
+class WriteTransaction : public BaseWriteTransaction {
  public:
   WriteTransaction(const tracked_objects::Location& from_here,
                    WriterTag writer,