[Sync] Convert sync to a static library.

components/sync/base/invalidation_interface.h

Index: components/sync/base/invalidation_interface.h
diff --git a/components/sync/base/invalidation_interface.h b/components/sync/base/invalidation_interface.h
index aacfb03dcca7bdb4f913eee3329bf79556381f92..8481749f931e565691ba8b25b6181d8566c0acd7 100644
--- a/components/sync/base/invalidation_interface.h
+++ b/components/sync/base/invalidation_interface.h
@@ -9,13 +9,11 @@
 
 #include <string>
 
-#include "components/sync/base/sync_export.h"
-
 namespace syncer {
 
 // An interface that wraps sync's interactions with the component that provides
 // it with invalidations.
-class SYNC_EXPORT InvalidationInterface {
+class InvalidationInterface {
  public:
   // Orders invalidations based on version number and IsUnknownVersion().
   static bool LessThanByVersion(const InvalidationInterface& a,