Adding UMA for daily video percent savings for data reduction proxy

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 d90322757fd9a3f32f4bff35372c620d43202740..848324de0b5dceb17f65deef33f7a1212cba91ac 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -85787,20 +85787,24 @@ To add a new entry, add it with any value and run test to compute valid value.
 
 <histogram_suffixes name="DataReductionProxy.MimeType">
   <suffix name="Application" label="Application mime-type"/>
   <suffix name="Unknown"
       label="Deprecated. Moved to UnknownMime in M46. Unknown mime-type"/>
   <suffix name="UnknownMime" label="Unknown mime-type"/>
   <suffix name="Video" label="Video mime-type"/>
   <affected-histogram name="Net.DailyContentLength"/>
   <affected-histogram name="Net.DailyContentLength_DataReductionProxyEnabled"/>
   <affected-histogram name="Net.DailyContentLength_ViaDataReductionProxy"/>
+  <affected-histogram
+      name="Net.DailyContentSavingPercent_DataReductionProxyEnabled"/>
+  <affected-histogram
+      name="Net.DailyContentSavingPercent_ViaDataReductionProxy"/>
   <affected-histogram name="Net.DailyOriginalContentLength"/>
   <affected-histogram
       name="Net.DailyOriginalContentLength_DataReductionProxyEnabled"/>
   <affected-histogram
       name="Net.DailyOriginalContentLength_ViaDataReductionProxy"/>
 </histogram_suffixes>
 
 <histogram_suffixes name="DataReductionProxy.NetworkTypes" separator=".">
   <suffix name="Unknown" label="On Unknown network"/>
   <suffix name="Ethernet" label="On Ethernet network"/>