Record the data use by content type

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 e3e89d63ec1d7b8480b0405e19f607339c11dc5d..1385d764e15c7716b1204120288d31842b787c99 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -9441,6 +9441,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <summary>Count of total bytes sent by the Chrome on the network.</summary>
 </histogram>
 
+<histogram name="DataUse.ContentType.Services" enum="DataUseContentType">
+  <owner>rajendrant@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Data use of Chrome services traffic by different content types. Recorded
+    when network bytes are received by Chrome.

[Mark P, 2016/12/22 23:27:17]

Please specify the unit somewhere here (bytes I assume).
ditto below

[Raj, 2016/12/24 03:55:54]

Done.

+  </summary>
+</histogram>
+
+<histogram name="DataUse.ContentType.UserTraffic" enum="DataUseContentType">
+  <owner>rajendrant@chromium.org</owner>
+  <owner>bengr@chromium.org</owner>
+  <summary>
+    Data use of user traffic by different content types. Recorded when network
+    bytes are rece\   ived by Chrome.

[Mark P, 2016/12/22 23:27:17]

editing error here?

[Raj, 2016/12/24 03:55:54]

Done.

+  </summary>
+</histogram>
+
 <histogram name="DataUse.MessageSize" units="bytes">
   <owner>amohammadkhan@chromium.org</owner>
   <owner>bengr@chromium.org</owner>
@@ -81433,6 +81451,22 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="8" label="Data use tracking ended dialog opted out"/>
 </enum>
 
+<enum name="DataUseContentType" type="int">
+  <int value="0" label="Other"/>
+  <int value="1" label="Mainframe HTML"/>
+  <int value="2" label="Non Mainframe HTML"/>
+  <int value="3" label="CSS"/>
+  <int value="4" label="Image"/>
+  <int value="5" label="Javascript"/>
+  <int value="6" label="Font"/>
+  <int value="7" label="Audio - App in background"/>
+  <int value="8" label="Audio - Tab in background"/>
+  <int value="9" label="Audio - Tab in foreground"/>
+  <int value="10" label="Video - App in background"/>
+  <int value="11" label="Video - Tab in background"/>
+  <int value="12" label="Video - Tab in foreground"/>
+</enum>
+
 <enum name="DataUseServices" type="int">
   <int value="0" label="Not Tagged"/>
   <int value="1" label="Suggestions"/>