Expose RTT and downlink bandwidth using experimental Javascript API

net/nqe/network_quality_estimator.cc

Index: net/nqe/network_quality_estimator.cc
diff --git a/net/nqe/network_quality_estimator.cc b/net/nqe/network_quality_estimator.cc
index e52cf68ce97795503dfaa9d24ba8f9f993e3f5c3..f495e3f4c0a7e08aab796a1eb8bdb9188ecc438e 100644
--- a/net/nqe/network_quality_estimator.cc
+++ b/net/nqe/network_quality_estimator.cc
@@ -293,6 +293,7 @@ NetworkQualityEstimator::NetworkQualityEstimator(
            NETWORK_QUALITY_OBSERVATION_SOURCE_HTTP_EXTERNAL_ESTIMATE,
            NETWORK_QUALITY_OBSERVATION_SOURCE_HTTP_CACHED_ESTIMATE,
            NETWORK_QUALITY_OBSERVATION_SOURCE_DEFAULT_HTTP_FROM_PLATFORM}),
+      suppress_notifications_for_testing_(false),
       weak_ptr_factory_(this) {
   // None of the algorithms can have an empty name.
   DCHECK(algorithm_name_to_enum_.end() ==
@@ -1587,6 +1588,10 @@ void NetworkQualityEstimator::NotifyObserversOfRTT(
   // Maybe recompute the effective connection type since a new RTT observation
   // is available.
   MaybeComputeEffectiveConnectionType();
+
+  if (suppress_notifications_for_testing_)
+    return;
+
   for (auto& observer : rtt_observer_list_) {
     observer.OnRTTObservation(observation.value.InMilliseconds(),
                               observation.timestamp, observation.source);
@@ -1605,6 +1610,10 @@ void NetworkQualityEstimator::NotifyObserversOfThroughput(
   // Maybe recompute the effective connection type since a new throughput
   // observation is available.
   MaybeComputeEffectiveConnectionType();
+
+  if (suppress_notifications_for_testing_)
+    return;
+
   for (auto& observer : throughput_observer_list_) {

[bengr, 2017/05/12 19:09:54]

I'd prefer that you didn't add test support into non-test code. Can you instead
put  the call to observer.OnThroughputObservation into its own virtualized
method? Alternatively, could you subclass the observer, virtualize
onThroughputObservation, and pass a subclass instance into NQE?

[tbansal1, 2017/05/12 22:18:17]

Done.

     observer.OnThroughputObservation(observation.value, observation.timestamp,
                                      observation.source);
@@ -1668,10 +1677,6 @@ void NetworkQualityEstimator::
   DCHECK(thread_checker_.CalledOnValidThread());
   DCHECK_NE(EFFECTIVE_CONNECTION_TYPE_LAST, effective_connection_type_);
 
-  // TODO(tbansal): Add hysteresis in the notification.
-  for (auto& observer : effective_connection_type_observer_list_)
-    observer.OnEffectiveConnectionTypeChanged(effective_connection_type_);
-
   // Add the estimates of the current network to the cache store.
   if (effective_connection_type_ != EFFECTIVE_CONNECTION_TYPE_UNKNOWN) {
     network_quality_store_->Add(current_network_id_,
@@ -1679,11 +1684,21 @@ void NetworkQualityEstimator::
                                     tick_clock_->NowTicks(), network_quality_,
                                     effective_connection_type_));
   }
+
+  if (suppress_notifications_for_testing_)
+    return;
+
+  // TODO(tbansal): Add hysteresis in the notification.

[bengr, 2017/05/12 19:09:55]

What kind of hysteresis? Consider making the hysteresis part of the observer.

[tbansal1, 2017/05/12 22:18:17]

Removed this. We can consider adding hysteresis in the observer interface at
some point. Currently, hysteresis already exists for the notifications sent from
the browser to the render processes.

+  for (auto& observer : effective_connection_type_observer_list_)
+    observer.OnEffectiveConnectionTypeChanged(effective_connection_type_);
 }
 
 void NetworkQualityEstimator::NotifyObserversOfRTTOrThroughputComputed() const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  if (suppress_notifications_for_testing_)

[bengr, 2017/05/12 19:09:55]

Yeah, this is gross. Virtualize.

[tbansal1, 2017/05/12 22:18:17]

Done.

+    return;
+
   // TODO(tbansal): Add hysteresis in the notification.
   for (auto& observer : rtt_and_throughput_estimates_observer_list_) {
     observer.OnRTTOrThroughputEstimatesComputed(
@@ -1696,6 +1711,8 @@ void NetworkQualityEstimator::NotifyEffectiveConnectionTypeObserverIfPresent(
     EffectiveConnectionTypeObserver* observer) const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  if (suppress_notifications_for_testing_)
+    return;
   if (!effective_connection_type_observer_list_.HasObserver(observer))
     return;
   if (effective_connection_type_ == EFFECTIVE_CONNECTION_TYPE_UNKNOWN)
@@ -1707,6 +1724,8 @@ void NetworkQualityEstimator::NotifyRTTAndThroughputEstimatesObserverIfPresent(
     RTTAndThroughputEstimatesObserver* observer) const {
   DCHECK(thread_checker_.CalledOnValidThread());
 
+  if (suppress_notifications_for_testing_)
+    return;
   if (!rtt_and_throughput_estimates_observer_list_.HasObserver(observer))
     return;
   observer->OnRTTOrThroughputEstimatesComputed(
@@ -1820,6 +1839,11 @@ const char* NetworkQualityEstimator::GetNameForStatistic(int i) const {
   return "";
 }
 
+void NetworkQualityEstimator::SuppressNotificationsForTesting() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  suppress_notifications_for_testing_ = true;
+}
+
 base::Optional<base::TimeDelta>
 NetworkQualityEstimator::NetworkQualityProvider::GetHttpRTT() const {
   return base::Optional<base::TimeDelta>();