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

sync/internal_api/sync_manager_impl.cc

Index: sync/internal_api/sync_manager_impl.cc
diff --git a/sync/internal_api/sync_manager_impl.cc b/sync/internal_api/sync_manager_impl.cc
index 3f5c370419e6646e55d44ffeb5612712449b7832..c2173a95644abecda73bc0b602c85f385b5ee498 100644
--- a/sync/internal_api/sync_manager_impl.cc
+++ b/sync/internal_api/sync_manager_impl.cc
@@ -920,6 +920,10 @@ SyncStatus SyncManagerImpl::GetDetailedStatus() const {
   return allstatus_.status();
 }
 
+void SyncManagerImpl::OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd) {
+  directory()->OnMemoryDump(pmd);
+}
+
 void SyncManagerImpl::SaveChanges() {
   directory()->SaveChanges();
 }