Record the time since Chromium is in background for background data use

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 2fbf786d0720efecba1eb895f1f01878170ba92b..033cdc5bb9697e3cb618c2e699550b486d791238 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -8803,6 +8803,27 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DataUse.BackgroundToDataRecievedPerByte" units="ms">
+  <owner>rajendrant@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    The time since Chrome is in background when background data use happens.
+    Recorded for each byte of background data use. The source of traffic whether
+    from user browsing or chrome services is added as suffix to this histogram.
+  </summary>
+</histogram>
+
+<histogram name="DataUse.BackgroundToFirstDownstream" units="ms">
+  <owner>rajendrant@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    The time since Chrome is in background when first background data use
+    happens. Recorded when first background downstream data use after Chrome is
+    in background. The source of traffic whether from user browsing or chrome
+    services is added as suffix to this histogram.
+  </summary>
+</histogram>
+
 <histogram name="DataUse.BytesReceived" units="bytes">
   <owner>tbansal@chromium.org</owner>
   <summary>Count of total bytes received by the Chrome on the network.</summary>
@@ -103756,6 +103777,13 @@ value.
   <affected-histogram name="DataUse.MessageSize"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="DataUse.TrafficSource" separator=".">
+  <suffix name="System"/>
+  <suffix name="User"/>
+  <affected-histogram name="DataUse.BackgroundToDataRecievedPerByte"/>
+  <affected-histogram name="DataUse.BackgroundToFirstDownstream"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="DefaultAppsExperiment">
   <suffix name="NoDefaultApps" label="User's without default apps installed"/>
   <suffix name="WithDefaultApps" label="User's with default apps installed"/>