sync: Use invalidation local acknowledgements

As of r237421, the invalidations system now supports a new and improved
form of local acknowledgements.  Any invalidations not explicitly
dropped or acknowledged will be redelivered after a restart.

This CL makes use of the new functionality in sync.  It uses the
DataTypeTrackers to track the status of pending invalidations and
acknowledge or drop invalidations as appropriate.

Also notable in this CL is that the 'server_dropped_hints' flag has now
been uncommented in the sync protocol.  We've known for a long time that
we wanted to support such a flag, but haven't been able to implement it
correctly until now.

BUG=78462,233437

Review URL: https://codereview.chromium.org/102353005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241170 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 17 insertions, 3 deletions

diff --git a/sync/internal_api/public/base/model_type_test_util.cc b/sync/internal_api/public/base/model_type_test_util.cc
index d9621bb..4876962 100644
--- a/sync/internal_api/public/base/model_type_test_util.cc
+++ b/sync/internal_api/public/base/model_type_test_util.cc
@@ -7,15 +7,22 @@
 
 namespace syncer {
 
-ObjectIdInvalidationMap BuildInvalidationMap(
+syncer::Invalidation BuildInvalidation(
     ModelType type,
     int version,
     const std::string& payload) {
-  ObjectIdInvalidationMap map;
   invalidation::ObjectId id;
   bool result = RealModelTypeToObjectId(type, &id);
   DCHECK(result);
-  map.Insert(Invalidation::Init(id, version, payload));
+  return Invalidation::Init(id, version, payload);
+}
+
+ObjectIdInvalidationMap BuildInvalidationMap(
+    ModelType type,
+    int version,
+    const std::string& payload) {
+  ObjectIdInvalidationMap map;
+  map.Insert(BuildInvalidation(type, version, payload));
   return map;
 }
 
diff --git a/sync/internal_api/public/base/model_type_test_util.h b/sync/internal_api/public/base/model_type_test_util.h
index c724bf5..1412f66 100644
--- a/sync/internal_api/public/base/model_type_test_util.h
+++ b/sync/internal_api/public/base/model_type_test_util.h
@@ -21,6 +21,13 @@ ObjectIdInvalidationMap BuildInvalidationMap(
     int version,
     const std::string& payload);
 
+// Builds an invalidation.  Similar to Invalidation::Init, but its first
+// parameter is a ModelType rather than an ObjectId.
+syncer::Invalidation BuildInvalidation(
+    ModelType type,
+    int version,
+    const std::string& payload);
+
 // Defined for googletest.  Forwards to ModelTypeSetToString().
 void PrintTo(ModelTypeSet model_types, ::std::ostream* os);