Add histograms for ExternalDataUseObserver

chrome/browser/android/data_usage/external_data_use_observer.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_H_
 #define CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_H_
 
 #include <jni.h>
 #include <stdint.h>
 
@@ skipping 85 matching lines @@
   bool MatchesAppPackageName(const std::string& app_package_name,
                              std::string* label) const;
 
   DataUseTabModel* data_use_tab_model() const {
     return data_use_tab_model_.get();
   }
 
  private:
   friend class DataUseTabModelTest;
   friend class ExternalDataUseObserverTest;
+  FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, DataUseReportTimedOut);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, SingleRegex);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, TwoRegex);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, MultipleRegex);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, ChangeRegex);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, LabelRemoved);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, MultipleMatchingRules);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, ReportsMergedCorrectly);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest,
                            TimestampsMergedCorrectly);
   FRIEND_TEST_ALL_PREFIXES(ExternalDataUseObserverTest, HashFunction);
@@ skipping 155 matching lines @@
   // expressions are applied to the request URLs, and filtered data use is
   // notified to |j_external_data_use_observer_|.
   base::android::ScopedJavaGlobalRef<jobject> j_external_data_use_observer_;
 
   // Maintains tab sessions.
   scoped_ptr<DataUseTabModel> data_use_tab_model_;
 
   // 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_| is null if no data use report is currently

[sclittle, 2015/12/02 19:07:54]

The NULL timeticks is a valid, real time; it shouldn't be used as a sentinel
value like this. You'll probably want to keep the bool you had before.

see
https://code.google.com/p/chromium/codesearch#chromium/src/base/time/time.h&l...

[tbansal1, 2015/12/03 03:19:45]

That applies only when doing Maths with TimeTicks. e.g., TimeTicks1 + TimeDelta
= TimeTicks2. It is possible that TimeTicks2 is 0.
But it is guaranteed that if TimeTicks has been initialized (without maths
operations), then it would have non null value.

+  // pending.
+  base::TimeTicks last_data_report_submitted_;

[sclittle, 2015/12/02 19:07:54]

nit: Name this so that it's obvious it's a point in time, e.g.
last_data_report_submitted_ticks_ or something.

[tbansal1, 2015/12/03 03:19:45]

Done.

+
+  // |pending_report_bytes_| is the total byte count in the data use report that
+  // is currently pending. |pending_report_bytes_| is 0 if no data use report is

[sclittle, 2015/12/02 19:07:54]

FYI: Be careful here - the DataUseAggregator could pass you DataUse objects with
both tx_bytes and rx_bytes of 0. It's fine to avoid submitting reports that are
0 bytes, but those will need to be filtered out right before reporting them.

[tbansal1, 2015/12/03 03:19:45]

Added an early return statement to filter out reports that have 0 bytes. Also,
changed the comment. Done.

+  // currently pending.
+  int64_t pending_report_bytes_;
 
   // Contains matching rules.
   std::vector<scoped_ptr<MatchingRule>> matching_rules_;
 
   // Buffered data reports that need to be submitted to the Java data use
   // observer.
   DataUseReports buffered_data_reports_;
 
   // True if |this| is currently registered as a data use observer.
   bool registered_as_observer_;
@@ skipping 16 matching lines @@
   // reports.
   int64_t total_bytes_buffered_;
 
   // Duration after which matching rules are periodically fetched.
   const base::TimeDelta fetch_matching_rules_duration_;
 
   // Minimum number of bytes that should be buffered before a data use report is
   // 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
   // IO and UI thread, respectively.
   base::WeakPtrFactory<ExternalDataUseObserver> io_weak_factory_;
   base::WeakPtrFactory<ExternalDataUseObserver> ui_weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ExternalDataUseObserver);
 };
 
 bool RegisterExternalDataUseObserver(JNIEnv* env);
 
 }  // namespace android
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_ANDROID_DATA_USAGE_EXTERNAL_DATA_USE_OBSERVER_H_