Added Network Quality Estimator Real-time interface to Cronet

net/base/network_quality_estimator.h

Index: net/base/network_quality_estimator.h
diff --git a/net/base/network_quality_estimator.h b/net/base/network_quality_estimator.h
index a32264f89703e90cfb600f25f82dad5ebbf8b6cc..6629145da6f07c041fdb84a617b4f0ee2bdfef22 100644
--- a/net/base/network_quality_estimator.h
+++ b/net/base/network_quality_estimator.h
@@ -13,7 +13,9 @@
 
 #include "base/gtest_prod_util.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "base/threading/thread_checker.h"
 #include "base/time/time.h"
 #include "net/base/external_estimate_provider.h"
@@ -36,6 +38,53 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
     : public NetworkChangeNotifier::ConnectionTypeObserver,
       public ExternalEstimateProvider::UpdatedEstimateDelegate {
  public:
+  // On Android, a Java counterpart will be generated for this enum.
+  // GENERATED_JAVA_ENUM_PACKAGE: org.chromium.net
+  // GENERATED_JAVA_CLASS_NAME_OVERRIDE: NetworkQualityObservationSource
+  // GENERATED_JAVA_PREFIX_TO_STRIP: OBSERVATION_SOURCE_
+  enum ObservationSource {
+    OBSERVATION_SOURCE_URL_REQUEST,
+    OBSERVATION_SOURCE_TCP,
+    OBSERVATION_SOURCE_QUIC,
+    OBSERVATION_SOURCE_CACHED_ESTIMATE,
+    OBSERVATION_SOURCE_DEFAULT_FROM_PLATFORM,

[pauljensen, 2015/09/02 16:54:48]

Each of these needs a comment explaining it.

[bengr, 2015/09/14 21:04:35]

Done.

+    OBSERVATION_SOURCE_EXTERNAL_ESTIMATE
+  };
+
+  // Observes measurements of round trip time.
+  class NET_EXPORT_PRIVATE RTTObserver {
+   public:
+    // Will be called when a new RTT observation is available. The round trip
+    // times is specified in milliseconds.

[pauljensen, 2015/09/02 16:54:48]

times->time

[bengr, 2015/09/14 21:04:35]

Done.

+    virtual void OnRTTObservation(int32_t rtt_ms,
+                                  const base::TimeTicks& timestamp,

[pauljensen, 2015/09/02 16:54:48]

You might want to explain what |timestamp| is a timestamp of...I'd imagine
OnRTTObservation() getting called immediately after an observation is taken, so
a timestamp of when the observation was taken seems redundant with
TimeTicks::Now().

[bengr, 2015/09/14 21:04:35]

Right. I wanted to decouple this so that there wouldn't be any confusion about
when the observation was taken and to save the observer the trouble of calling
Now(). I'd imagine that observers might queue observations, so it's also a
convenience to have the timestamp. Moreover, I wasn't completely sure that
observations would always be reported immediately after being made.

+                                  ObservationSource source) = 0;
+
+   protected:
+    RTTObserver() {}
+    virtual ~RTTObserver() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(RTTObserver);
+  };
+
+  // Observes measurements of throughput.
+  class NET_EXPORT_PRIVATE ThroughputObserver {
+   public:
+    // Will be called when a new throughput observation is available.
+    // Throughput is specified in kilobits per second.
+    virtual void OnThroughputObservation(int32_t throughput_kbps,
+                                         const base::TimeTicks& timestamp,
+                                         ObservationSource source) = 0;
+
+   protected:
+    ThroughputObserver() {}
+    virtual ~ThroughputObserver() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(ThroughputObserver);
+  };
+
   // Creates a new NetworkQualityEstimator.
   // |variation_params| is the map containing all field trial parameters
   // related to NetworkQualityEstimator field trial.
@@ -76,6 +125,29 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
       const base::TimeTicks& begin_timestamp,
       int32_t* kbps) const;
 
+  // Adds |rtt_observer| to the list of round trip time observers. Must be
+  // called on the IO thread.
+  void AddRTTObserver(RTTObserver* rtt_observer);
+
+  // Removes |rtt_observer| from the list of round trip time observers if it
+  // is on the list of observers. Must be called on the IO thread.
+  void RemoveRTTObserver(RTTObserver* rtt_observer);
+
+  // Adds |throughput_observer| to the list of throughput observers. Must be
+  // called on the IO thread.
+  void AddThroughputObserver(ThroughputObserver* throughput_observer);
+
+  // Removes |throughput_observer| from the list of throughput observers if it
+  // is on the list of observers. Must be called on the IO thread.
+  void RemoveThroughputObserver(ThroughputObserver* throughput_observer);
+
+  // Configure for testing. If true, |allow_local_host_requests| will include
+  // observations from localhost, and |allow_smaller_responses| will remove
+  // the requirement of throughtput observations that response size be above
+  // a threshold.
+  void ConfigureForTests(bool allow_local_host_requests,
+                         bool allow_smaller_responses);
+
  protected:
   // NetworkID is used to uniquely identify a network.
   // For the purpose of network quality estimation and caching, a network is
@@ -213,9 +285,15 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   };
 
   // Records the round trip time or throughput observation, along with the time
-  // the observation was made.
+  // the observation was made. The units of value are type specific. For round
+  // trip time observations, the value is in milliseconds. For throughput,
+  // the value is in kilobits per second. Observations can be made at several
+  // places in the network stack, thus the observation source is provided as
+  // well.
   struct NET_EXPORT_PRIVATE Observation {
-    Observation(int32_t value, base::TimeTicks timestamp);
+    Observation(int32_t value,
+                base::TimeTicks timestamp,
+                ObservationSource source);
     ~Observation();
 
     // Value of the observation.
@@ -223,6 +301,9 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
 
     // Time when the observation was taken.
     const base::TimeTicks timestamp;
+
+    // The source of the observation.
+    const ObservationSource source;
   };
 
   // Holds an observation and its weight.
@@ -378,6 +459,10 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   // Writes the estimated quality of the current network to the cache.
   void CacheNetworkQualityEstimate();
 
+  void NotifyObserversOfRTT(const Observation& observation);
+
+  void NotifyObserversOfThroughput(const Observation& observation);
+
   // Records the UMA related to RTT.
   void RecordRTTUMA(int32_t estimated_value_msec,
                     int32_t actual_value_msec) const;
@@ -389,12 +474,12 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
 
   // Determines if the requests to local host can be used in estimating the
   // network quality. Set to true only for tests.
-  const bool allow_localhost_requests_;
+  bool allow_localhost_requests_;
 
   // Determines if the responses smaller than |kMinTransferSizeInBytes|
   // or shorter than |kMinTransferSizeInBytes| can be used in estimating the
   // network quality. Set to true only for tests.
-  const bool allow_small_responses_;
+  bool allow_small_responses_;
 
   // Time when last connection change was observed.
   base::TimeTicks last_connection_change_;
@@ -432,6 +517,10 @@ class NET_EXPORT_PRIVATE NetworkQualityEstimator
   // system APIs. May be NULL.
   const scoped_ptr<ExternalEstimateProvider> external_estimates_provider_;
 
+  // Observer lists for round trip times and throughput measurements.
+  base::ObserverList<RTTObserver> rtt_observer_list_;
+  base::ObserverList<ThroughputObserver> throughput_observer_list_;
+
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualityEstimator);