UMA for data savings displayed to users.

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 0f2d932091d213ca8706a6fbe0d12498ecce7720..0a062c35dbccd35d41c0ffa2f5e6d978aafc058d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -19408,6 +19408,28 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Net.DailyUserVisibleSavingsBytes_DataRedictionProxyEnabled"

[Alexei Svitkine (slow), 2015/06/05 15:46:53]

Nit: It's misleading to have "Bytes" in the name, if the unit is KB. Either
change to KB or omit that substring entirely.

[Not at Google. Contact bengr, 2015/06/05 17:59:42]

Changed to "Size". WDYT?

+    units="KB">
+  <owner>kundaji@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    The total data saved in KB in past
+    |DataReductionProxy::kNumDaysInHistorySummary| days. This number is used to
+    compute the data savings displayed to the user.
+  </summary>
+</histogram>
+
+<histogram name="Net.DailyUserVisibleSavingsPercent_DataRedictionProxyEnabled"
+    units="Percent">
+  <owner>kundaji@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    The percentage of data savings in past
+    |DataReductionProxy::kNumDaysInHistorySummary| days. This number is
+    displayed to users as their data savings.
+  </summary>
+</histogram>
+
 <histogram name="Net.DhcpWpadCancelTime" units="milliseconds">
   <obsolete>
     Removed in Chrome 39.