sync: Expose DirectoryDebugInfoEmitters in engine

sync/engine/directory_commit_contribution.h

Index: sync/engine/directory_commit_contribution.h
diff --git a/sync/engine/directory_commit_contribution.h b/sync/engine/directory_commit_contribution.h
index 83cefe9d4970c9266f19db885c75633ededc131f..0b15358320473eff4f8bd1dec340c80fc45246fc 100644
--- a/sync/engine/directory_commit_contribution.h
+++ b/sync/engine/directory_commit_contribution.h
@@ -14,6 +14,7 @@
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/util/syncer_error.h"
 #include "sync/protocol/sync.pb.h"
+#include "sync/sessions/directory_type_debug_info_emitter.h"
 #include "sync/sessions/status_controller.h"
 
 namespace syncer {
@@ -47,7 +48,8 @@ class SYNC_EXPORT_PRIVATE DirectoryCommitContribution
   static scoped_ptr<DirectoryCommitContribution> Build(
       syncable::Directory* dir,
       ModelType type,
-      size_t max_items);
+      size_t max_items,
+      DirectoryTypeDebugInfoEmitter* debug_info_emitter);
 
   // Serialize this contribution's entries to the given commit request |msg|.
   //
@@ -83,7 +85,8 @@ class SYNC_EXPORT_PRIVATE DirectoryCommitContribution
       const std::vector<int64>& metahandles,
       const google::protobuf::RepeatedPtrField<sync_pb::SyncEntity>& entities,
       const sync_pb::DataTypeContext& context,
-      syncable::Directory* directory);
+      syncable::Directory* directory,
+      DirectoryTypeDebugInfoEmitter* debug_info_emitter);
 
   void UnsetSyncingBits();
 
@@ -99,6 +102,9 @@ class SYNC_EXPORT_PRIVATE DirectoryCommitContribution
   // called.  This flag must be unset by the time our destructor is called.
   bool syncing_bits_set_;
 
+  // A pointer to the commit counters of our parent CommitContributor.
+  DirectoryTypeDebugInfoEmitter* debug_info_emitter_;
+
   DISALLOW_COPY_AND_ASSIGN(DirectoryCommitContribution);
 };