Add histograms for data usage

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 49aa452bbb54c688253b4ddd0676e913634e60bf..b15a12a6f9c87a88a181350708e3802e48034d9e 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -6566,6 +6566,56 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="DataUsage.MatchingRulesCount.Invalid" units="count">
+  <owner>bengr@chromium.org</owner>
+  <owner>rajendrant@chromium.org</owner>
+  <summary>
+    The number of invalid matching rules fetched from the platform external data
+    use observer. A sample is recorded everytime fetch done callback is called.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.MatchingRulesCount.Valid" units="count">
+  <owner>bengr@chromium.org</owner>
+  <owner>rajendrant@chromium.org</owner>
+  <summary>
+    The number of valid matching rules fetched from the platform external data
+    use observer. A sample is recorded everytime fetch done callback is called.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.Perf.MatchingRuleFirstFetchDuration"
+    units="millsecond">

[Steven Holte, 2016/01/15 23:17:28]

units="ms"

[Raj, 2016/01/16 00:47:00]

Done.

+  <owner>bengr@chromium.org</owner>
+  <owner>rajendrant@chromium.org</owner>
+  <summary>
+    The time taken to fetch the matching rules for the first time from the
+    platform external data use observer. This measures the duration from the
+    start time of Chromium to the time the rules are returned asynchronously. A
+    sample is recorded when the first fetch done callback is called.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.Perf.ReportSubmissionDuration" units="millisecond">
+  <owner>bengr@chromium.org</owner>
+  <owner>rajendrant@chromium.org</owner>
+  <summary>
+    The time taken to submit the data use reports to the platform external data
+    use observer. This measures the duration from the time of report submission
+    to the time report submission done asynchronous callback is received. A
+    sample is recorded everytime report submission done callback is received.
+  </summary>
+</histogram>
+
+<histogram name="DataUsage.Perf.URLRegexMatchDuration" units="millisecond">
+  <owner>bengr@chromium.org</owner>
+  <owner>rajendrant@chromium.org</owner>
+  <summary>
+    The time taken for a regular expression to parse an URL. A sample is
+    recorded evertime regular expression parsing is done for an URL.
+  </summary>
+</histogram>
+
 <histogram name="DataUsage.ReportSubmission.Bytes" units="bytes">
   <owner>bengr@chromium.org</owner>
   <owner>tbansal@chromium.org</owner>