Add histograms for ExternalDataUseObserver

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 c64c1d168cbb6d54009b88f8495ee7bccee92733..ce1a09714ff16ee5dff1a0cb0d2af705ea12ab57 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -6443,6 +6443,57 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DataUsage.ReportSubmission.Failed.Bytes" units="bytes">
+  <owner>bengr@chromium.org</owner>
+  <owner>tbansal@chromium.org</owner>
+  <summary>
+    Count of bytes in the data use reports that were submitted to the platform
+    external data use observer, and the platform external data use observer
+    notified that the submission failed. Recorded every time the platform
+    external data use observer notifies that submission of data use report
+    failed. This does not include the reports that timed-out.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.ReportSubmission.Lost.Bytes" units="bytes">
+  <owner>bengr@chromium.org</owner>
+  <owner>tbansal@chromium.org</owner>
+  <summary>
+    Count of bytes in the data use reports that were lost before an attempt is
+    made to submit it to the C++ external data use observer. Recorded every time
+    a report is lost before an attempt is made to submit it to the external data
+    use observer. A submission may be lost if the data use report could not be
+    buffered due to internal buffers being full.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.ReportSubmission.Successful.Bytes" units="bytes">
+  <owner>bengr@chromium.org</owner>
+  <owner>tbansal@chromium.org</owner>
+  <summary>
+    Count of bytes in the data use reports that were submitted to the platform
+    external data use observer and the platform external data use observer
+    notified that the submission was successful.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.ReportSubmission.TimedOut.Bytes" units="bytes">

[Alexei Svitkine (slow), 2015/12/09 18:15:47]

I suggest switching the order of the suffixes - i.e to
"DataUsage.ReportSubmission.Bytes.TimedOut".

Then, you can use the <histogram_suffixes> feature in the XML file to reduce the
verbosity of these definitions. See comment at top of file on how to use it.

+  <owner>bengr@chromium.org</owner>
+  <owner>tbansal@chromium.org</owner>
+  <summary>
+    Count of bytes in the data use reports whose submission to the platform
+    external data use observer timed out. Recorded every time submission of a
+    report to the platform external data use observer times out.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.ReportSubmissionResult"
+    enum="DataUsageReportSubmissionResult">
+  <owner>bengr@chromium.org</owner>
+  <owner>tbansal@chromium.org</owner>
+  <summary>Result of data usage report submission.</summary>
+</histogram>
+
 <histogram name="DataUse.MessageSize" units="bytes">
   <owner>amohammadkhan@chromium.org</owner>
   <owner>bengr@chromium.org</owner>
@@ -58384,6 +58435,13 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="10" label="Diabled directly from the First Run Experience"/>
 </enum>
 
+<enum name="DataUsageReportSubmissionResult" type="int">
+  <int value="0" label="Successful"/>
+  <int value="1" label="Failed"/>
+  <int value="2" label="Timed out"/>
+  <int value="3" label="Lost"/>
+</enum>
+
 <enum name="DataUseServices" type="int">
   <int value="0" label="Not Tagged"/>
   <int value="1" label="Suggestions"/>