sync: Implement per-type GetCommitIds

sync/engine/commit.cc

Index: sync/engine/commit.cc
diff --git a/sync/engine/commit.cc b/sync/engine/commit.cc
index f7f1e74d99e0789eeeef0771ae7c23e5d2137a07..85e5f949d38270e116c211c619a396087bad4e86 100644
--- a/sync/engine/commit.cc
+++ b/sync/engine/commit.cc
@@ -6,8 +6,9 @@
 
 #include "base/debug/trace_event.h"
 #include "sync/engine/build_commit_command.h"
-#include "sync/engine/get_commit_ids_command.h"
+#include "sync/engine/get_commit_ids.h"
 #include "sync/engine/process_commit_response_command.h"
+#include "sync/engine/syncer.h"
 #include "sync/engine/syncer_proto_util.h"
 #include "sync/sessions/sync_session.h"
 #include "sync/syncable/mutable_entry.h"
@@ -76,11 +77,7 @@ bool PrepareCommitMessage(
 
   // Fetch the items to commit.
   const size_t batch_size = session->context()->max_commit_batch_size();
-  GetCommitIdsCommand get_commit_ids_command(&trans,
-                                             requested_types,
-                                             batch_size,
-                                             commit_set);
-  get_commit_ids_command.Execute(session);
+  GetCommitIds(&trans, requested_types, batch_size, commit_set);
 
   DVLOG(1) << "Commit message will contain " << commit_set->Size() << " items.";
   if (commit_set->Empty()) {