Measuring data use of different ModelTypes in Sync Service.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 4cbed3453d0310875041e9fc37034b89906dede8..4b30dbbd2458d4029d99692a34b27820f78fba00 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -5234,6 +5234,46 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DataUse.Sync.Download.Bytes" enum="SyncModelTypes">
+  <owner>amohammadkhan@chromium.org</owner>
+  <summary>
+    Number of downloaded bytes of different data types in Sync service for
+    received updates.
+  </summary>
+</histogram>
+
+<histogram name="DataUse.Sync.Download.Count" enum="SyncModelTypes">
+  <owner>amohammadkhan@chromium.org</owner>
+  <summary>
+    Number of downloaded entities of different data types in Sync service for
+    received updates.
+  </summary>
+</histogram>
+
+<histogram name="DataUse.Sync.ProgressMarker.Bytes" enum="SyncModelTypes">
+  <owner>amohammadkhan@chromium.org</owner>
+  <summary>
+    Number of downloaded bytes of ProgressMarker of different data types in Sync
+    service for received updates.
+  </summary>
+</histogram>
+
+<histogram name="DataUse.Sync.Upload.Bytes" enum="SyncModelTypes">
+  <owner>amohammadkhan@chromium.org</owner>
+  <summary>
+    Number of uploaded bytes of different data types in Sync service for sent
+    commits.
+  </summary>
+</histogram>
+
+<histogram name="DataUse.Sync.Upload.Count" enum="SyncModelTypes">
+  <owner>amohammadkhan@chromium.org</owner>
+  <summary>
+    Number of uploaded entities of different data types in Sync service for sent
+    commits.
+  </summary>
+</histogram>
+
 <histogram name="DataUse.User" units="bytes">
   <owner>amohammadkhan@chromium.org</owner>
   <summary>