[WIP][tracing] Add memory dump provider for sync Directory

sync/internal_api/public/test/fake_sync_manager.h

Index: sync/internal_api/public/test/fake_sync_manager.h
diff --git a/sync/internal_api/public/test/fake_sync_manager.h b/sync/internal_api/public/test/fake_sync_manager.h
index 01b537f3f7818bd9eb561848bae4bc6f6990caaf..63a80228cff06c2849c26bb57a620dad4852bab2 100644
--- a/sync/internal_api/public/test/fake_sync_manager.h
+++ b/sync/internal_api/public/test/fake_sync_manager.h
@@ -95,6 +95,7 @@ class FakeSyncManager : public SyncManager {
   void AddObserver(Observer* observer) override;
   void RemoveObserver(Observer* observer) override;
   SyncStatus GetDetailedStatus() const override;
+  void OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd) override;
   void SaveChanges() override;
   void ShutdownOnSyncThread(ShutdownReason reason) override;
   UserShare* GetUserShare() override;