[Sync] Convert sync to a static library.

components/sync/base/invalidation_interface.h

 // Copyright 2014 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_BASE_INVALIDATION_INTERFACE_H_
 #define COMPONENTS_SYNC_BASE_INVALIDATION_INTERFACE_H_
 
 #include <stdint.h>
 
 #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,
                                 const InvalidationInterface& b);
 
   InvalidationInterface();
   virtual ~InvalidationInterface();
 
   // Returns true if this is an 'unknown version' invalidation.
   // Such invalidations have no valid payload or version number.
@@ skipping 18 matching lines @@
   // drop this invalidation.
   //
   // To indicate recovery from a drop event, the receiver of this invalidation
   // will call Acknowledge() on the most recently dropped invalidation.
   virtual void Drop() = 0;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_BASE_INVALIDATION_INTERFACE_H_