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

sync/internal_api/test/fake_sync_manager.cc

Index: sync/internal_api/test/fake_sync_manager.cc
diff --git a/sync/internal_api/test/fake_sync_manager.cc b/sync/internal_api/test/fake_sync_manager.cc
index a0883f893935f3ea275ebaa26ba22de62ce46257..447cfa534afb5cd61e8273792a1f9a8eae98628a 100644
--- a/sync/internal_api/test/fake_sync_manager.cc
+++ b/sync/internal_api/test/fake_sync_manager.cc
@@ -189,6 +189,10 @@ SyncStatus FakeSyncManager::GetDetailedStatus() const {
   return SyncStatus();
 }
 
+void FakeSyncManager::OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd) {
+  NOTIMPLEMENTED();
+}
+
 void FakeSyncManager::SaveChanges() {
   // Do nothing.
 }