Measuring data use of different ModelTypes in Sync Service.

sync/engine/process_updates_util.cc

Index: sync/engine/process_updates_util.cc
diff --git a/sync/engine/process_updates_util.cc b/sync/engine/process_updates_util.cc
index 9b428ef929bd9c8ba80705e028dd91f8ce2a39bb..ad0d30292dbb49c6ab0524bd041d4fb943f6ffed 100644
--- a/sync/engine/process_updates_util.cc
+++ b/sync/engine/process_updates_util.cc
@@ -15,6 +15,7 @@
 #include "sync/syncable/syncable_proto_util.h"
 #include "sync/syncable/syncable_util.h"
 #include "sync/util/cryptographer.h"
+#include "sync/util/data_type_histogram.h"
 
 namespace syncer {
 
@@ -303,6 +304,13 @@ void ProcessDownloadedUpdates(
     if (verify_result != VERIFY_SUCCESS && verify_result != VERIFY_UNDELETE)
       continue;
     ProcessUpdate(**update_it, dir->GetCryptographer(trans), trans);
+    if ((*update_it)->ByteSize() > 0) {
+      SYNC_RECORD_DATATYPE_BIN("DataUse.Sync.Download.Bytes",
+                               ModelTypeToHistogramInt(type),
+                               (*update_it)->ByteSize());
+    }
+    UMA_HISTOGRAM_SPARSE_SLOWLY("DataUse.Sync.Download.Count",
+                                ModelTypeToHistogramInt(type));
   }
 }