sync: Implement per-type commit interface

sync/engine/commit.h

Index: sync/engine/commit.h
diff --git a/sync/engine/commit.h b/sync/engine/commit.h
index 168d950c276a1242695cb70f476dcc0845c2672b..c5fcc62f19baa1a55c76a228f7eb42c6c706bf9e 100644
--- a/sync/engine/commit.h
+++ b/sync/engine/commit.h
@@ -5,15 +5,31 @@
 #ifndef SYNC_ENGINE_COMMIT_H_
 #define SYNC_ENGINE_COMMIT_H_
 
+#include <map>
+
+#include "base/stl_util.h"
+#include "sync/base/sync_export.h"
+#include "sync/engine/sync_directory_commit_contributor.h"
 #include "sync/internal_api/public/base/model_type.h"
+#include "sync/internal_api/public/engine/model_safe_worker.h"
 #include "sync/internal_api/public/util/syncer_error.h"
+#include "sync/protocol/sync.pb.h"
+#include "sync/util/extensions_activity.h"
+
+namespace sync_pb {
+class ClientToServerMessage;
+class ClientToServerResponse;
+}
 
 namespace syncer {
 
 namespace sessions {
+class StatusController;
 class SyncSession;
 }
 
+class SyncDirectoryCommitContribution;
+class SyncDirectoryCommitContributor;
 class Syncer;
 
 // This function will commit batches of unsynced items to the server until the
@@ -33,6 +49,46 @@ SyncerError BuildAndPostCommits(
     Syncer* syncer,
     sessions::SyncSession* session);
 
+// This class wraps the actions related to building and executing a single
+// commit operation.
+//
+// This class' most important responsibility is to manage the ContributionsMap.
+// This class serves as a container for those objects.  Although it would have
+// been acceptable to let this class be a dumb container object, it turns out
+// that there was no other convenient place to put the Init() and
+// PostAndProcessCommitResponse() functions.  So they ended up here.
+class SYNC_EXPORT_PRIVATE Commit {
+ public:
+  static Commit* Init(
+      ModelTypeSet requested_types,
+      CommitContributorMap* contributor_map,
+      size_t max_entries,
+      const std::string& account_name,
+      const std::string& cache_guid,
+      ExtensionsActivity* extensions_activity);
+
+  explicit Commit(
+      std::map<ModelType, SyncDirectoryCommitContribution*> contributions,
+      sync_pb::ClientToServerMessage message,
+      ExtensionsActivity::Records extensions_activity_buffer);
+  ~Commit();
+
+  SyncerError PostAndProcessResponse(
+      sessions::SyncSession* session,
+      sessions::StatusController* status,
+      ExtensionsActivity* extensions_activity);
+
+ private:
+  typedef std::map<ModelType, SyncDirectoryCommitContribution*> ContributionMap;
+
+  ContributionMap contributions_;
+  STLValueDeleter<ContributionMap> deleter_;
+
+  sync_pb::ClientToServerMessage message_;
+  sync_pb::ClientToServerResponse response_;
+  ExtensionsActivity::Records extensions_activity_buffer_;
+};
+
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_COMMIT_H_