Add histograms for ExternalDataUseObserver

chrome/browser/android/data_usage/external_data_use_observer.h

Index: chrome/browser/android/data_usage/external_data_use_observer.h
diff --git a/chrome/browser/android/data_usage/external_data_use_observer.h b/chrome/browser/android/data_usage/external_data_use_observer.h
index 2cb052439b16fae87f43a9ca64799d17e8c52dd5..8e62156e986f06892c23b0af1dea75373d4d5266 100644
--- a/chrome/browser/android/data_usage/external_data_use_observer.h
+++ b/chrome/browser/android/data_usage/external_data_use_observer.h
@@ -54,6 +54,19 @@ class DataUseTabModel;
 // TODO(tbansal): Create an inner class that manages the UI and IO threads.
 class ExternalDataUseObserver : public data_usage::DataUseAggregator::Observer {
  public:
+  // Result of data usage report submission.

[sclittle, 2015/12/08 00:36:21]

nit: mention that this should be kept in sync with the histograms.xml enum

[tbansal1, 2015/12/08 02:01:25]

Done.

+  enum DataUsageReportSubmissionResult {
+    // Submission of data use report to the external observer was successful.
+    DATAUSAGE_REPORT_SUBMISSION_SUCCESSFUL = 0,
+    // Submission of data use report to the external observer returned error.
+    DATAUSAGE_REPORT_SUBMISSION_FAILED = 1,
+    // Submission of data use report to the external observer timed out.
+    DATAUSAGE_REPORT_SUBMISSION_TIMED_OUT = 2,
+    // Data use report was lost before an attempt was made to submit it.
+    DATAUSAGE_REPORT_SUBMISSION_LOST = 3,
+    DATAUSAGE_REPORT_SUBMISSION_BOUNDARY = 4

[sclittle, 2015/12/08 00:36:21]

nit: isn't the typical naming for this "..._MAX"?

[tbansal1, 2015/12/08 02:01:25]

Done. Not sure, I have seen both.

+  };
+
   // External data use observer field trial name.
   static const char kExternalDataUseObserverFieldTrial[];
 
@@ -103,10 +116,10 @@ class ExternalDataUseObserver : public data_usage::DataUseAggregator::Observer {
  private:
   friend class DataUseTabModelTest;
   friend class ExternalDataUseObserverTest;
-  FRIEND_TEST_ALL_PREFIXES(DataUseUITabModelTest, ReportTabEventsTest);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, BufferDataUseReports);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, BufferSize);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, ChangeRegex);
+  FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, DataUseReportTimedOut);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, HashFunction);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, LabelRemoved);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, MultipleMatchingRules);
@@ -114,6 +127,7 @@ class ExternalDataUseObserver : public data_usage::DataUseAggregator::Observer {
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest,
                            PeriodicFetchMatchingRules);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, ReportsMergedCorrectly);
+  FRIEND_TEST_ALL_PREFIXES(DataUseUITabModelTest, ReportTabEventsTest);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, SingleRegex);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest,
                            TimestampsMergedCorrectly);
@@ -279,8 +293,14 @@ class ExternalDataUseObserver : public data_usage::DataUseAggregator::Observer {
   // True if callback from |FetchMatchingRulesDone| is currently pending.
   bool matching_rules_fetch_pending_;
 
-  // True if callback from |SubmitDataUseReportCallback| is currently pending.
-  bool submit_data_report_pending_;
+  // Time when the currently pending data use report was submitted.
+  // |last_data_report_submitted_ticks_| is null if no data use report is
+  // currently pending.
+  base::TimeTicks last_data_report_submitted_ticks_;
+
+  // |pending_report_bytes_| is the total byte count in the data use report that
+  // is currently pending.
+  int64_t pending_report_bytes_;
 
   // Contains matching rules.
   std::vector<scoped_ptr<MatchingRule>> matching_rules_;
@@ -317,6 +337,10 @@ class ExternalDataUseObserver : public data_usage::DataUseAggregator::Observer {
   // submitted.
   const int64_t data_use_report_min_bytes_;
 
+  // If a data use report is pending for more than |data_report_submit_timeout_|
+  // duration, it is considered as timed out.
+  const base::TimeDelta data_report_submit_timeout_;
+
   base::ThreadChecker thread_checker_;
 
   // |io_weak_factory_| and |ui_weak_factory_| are used for posting tasks on the