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..f1da9d8b10e707301b46cf0289a20e706b391cf9 100644
--- a/sync/engine/process_updates_util.cc
+++ b/sync/engine/process_updates_util.cc
@@ -5,6 +5,7 @@
 #include "sync/engine/process_updates_util.h"
 
 #include "base/location.h"
+#include "base/metrics/sparse_histogram.h"
 #include "sync/engine/syncer_proto_util.h"
 #include "sync/engine/syncer_types.h"
 #include "sync/engine/syncer_util.h"
@@ -16,6 +17,13 @@
 #include "sync/syncable/syncable_util.h"
 #include "sync/util/cryptographer.h"
 
+#define UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE(name, sample, value)     \
+  do {                                                                  \
+    base::HistogramBase* histogram = base::SparseHistogram::FactoryGet( \
+        name, base::HistogramBase::kUmaTargetedHistogramFlag);          \
+    histogram->AddCount(sample, value);                                 \
+  } while (0)
+
 namespace syncer {
 
 using sessions::StatusController;
@@ -303,6 +311,14 @@ void ProcessDownloadedUpdates(
     if (verify_result != VERIFY_SUCCESS && verify_result != VERIFY_UNDELETE)
       continue;
     ProcessUpdate(**update_it, dir->GetCryptographer(trans), trans);
+    if ((*update_it)->ByteSize() > 0) {
+      UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE("DataUse.Sync.Download.Bytes",
+                                             ModelTypeToHistogramInt(type),
+                                             (*update_it)->ByteSize());
+    }
+    UMA_HISTOGRAM_SPARSE_SLOWLY_WITH_VALUE("DataUse.Sync.Download.Count",
+                                           ModelTypeToHistogramInt(type),
+                                           1);
   }
 }