Record the offscreen playing duration of autoplaying muted videos

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
index bff62e7bfdb250473405fbd5bc2215a8d99b8bf2..397660f1dade78672e5f00d3dbbaa93ac6f71e34 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -293,6 +293,9 @@ enum AutoplaySource {
     NumberOfAutoplaySources = 2,
 };
 
+static const double maxUmaDuration = 10000;
+static const double umaBucketCount = 50;
+
 } // anonymous namespace
 
 class HTMLMediaElement::AutoplayHelperClientImpl :
@@ -448,6 +451,11 @@ HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName, Document& docum
     , m_playPromiseResolveTask(CancellableTaskFactory::create(this, &HTMLMediaElement::resolveScheduledPlayPromises))
     , m_playPromiseRejectTask(CancellableTaskFactory::create(this, &HTMLMediaElement::rejectScheduledPlayPromises))
     , m_audioSourceNode(nullptr)
+    , m_mutedVideoAutoplayStartTimeMS(0)
+    , m_mutedVideoAutoplayOffscreenDurationMS(0)
+    , m_isVisible(false)
+    , m_isAutoplayFromAttribute(false)
+    , m_autoplayOffscreenVisibilityObserver(nullptr)
     , m_autoplayHelperClient(AutoplayHelperClientImpl::create(this))
     , m_autoplayHelper(AutoplayExperimentHelper::create(m_autoplayHelperClient.get()))
     , m_remotePlaybackClient(nullptr)
@@ -472,6 +480,7 @@ HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName, Document& docum
 
 HTMLMediaElement::~HTMLMediaElement()
 {
+    maybeRecordMutedVideoAutoplayOffscreenDuration();
     MEDIA_LOG << "~HTMLMediaElement(" << (void*)this << ")";
 
     // m_audioSourceNode is explicitly cleared by AudioNode::dispose().
@@ -1640,6 +1649,7 @@ void HTMLMediaElement::setReadyState(ReadyState state)
 
         // Check for autoplay, and record metrics about it if needed.
         if (shouldAutoplay(RecordMetricsBehavior::DoRecord)) {
+            m_isAutoplayFromAttribute = true;
             recordAutoplaySourceMetric(AutoplaySourceAttribute);
 
             // If the autoplay experiment says that it's okay to play now,
@@ -2090,6 +2100,7 @@ Nullable<ExceptionCode> HTMLMediaElement::play()
     m_autoplayHelper->playMethodCalled();
 
     if (!UserGestureIndicator::processingUserGesture()) {
+        m_isAutoplayFromAttribute = false;
         recordAutoplaySourceMetric(AutoplaySourceMethod);
         if (isGestureNeededForPlayback()) {
             // If playback is deferred, then don't start playback but don't
@@ -2192,6 +2203,7 @@ void HTMLMediaElement::pauseInternal()
         scheduleTimeupdateEvent(false);
         scheduleEvent(EventTypeNames::pause);
         scheduleRejectPlayPromises(AbortError);
+        maybeRecordMutedVideoAutoplayOffscreenDuration();
     }
 
     updatePlayState();
@@ -2905,6 +2917,7 @@ void HTMLMediaElement::timeChanged()
                 // changes paused to true and fires a simple event named pause at the media element.
                 m_paused = true;
                 scheduleEvent(EventTypeNames::pause);
+                maybeRecordMutedVideoAutoplayOffscreenDuration();
             }
             // Queue a task to fire a simple event named ended at the media element.
             scheduleEvent(EventTypeNames::ended);
@@ -3668,6 +3681,7 @@ DEFINE_TRACE(HTMLMediaElement)
     visitor->trace(m_autoplayHelper);
     visitor->trace(m_srcObject);
     visitor->trace(m_autoplayVisibilityObserver);
+    visitor->trace(m_autoplayOffscreenVisibilityObserver);
     visitor->template registerWeakMembers<HTMLMediaElement, &HTMLMediaElement::clearWeakMembers>(this);
     Supplementable<HTMLMediaElement>::trace(visitor);
     HTMLElement::trace(visitor);
@@ -3915,6 +3929,45 @@ void HTMLMediaElement::onVisibilityChangedForAutoplay(bool isVisible)
 
     m_autoplayVisibilityObserver->stop();
     m_autoplayVisibilityObserver = nullptr;
+    m_mutedVideoAutoplayStartTimeMS = monotonicallyIncreasingTimeMS();
+    m_isVisible = true;
+    m_autoplayOffscreenVisibilityObserver = new ElementVisibilityObserver(this, WTF::bind(&HTMLMediaElement::onVisibilityChangedForAutoplayOffscreen, wrapPersistent(this)));
+}
+
+void HTMLMediaElement::onVisibilityChangedForAutoplayOffscreen(bool isVisible)
+{
+    if (isVisible == m_isVisible)
+        return;
+
+    if (isVisible)
+        m_mutedVideoAutoplayStartTimeMS = monotonicallyIncreasingTimeMS();
+    else
+        m_mutedVideoAutoplayOffscreenDurationMS += monotonicallyIncreasingTimeMS() - m_mutedVideoAutoplayStartTimeMS;
+
+    m_isVisible = isVisible;
+}
+
+void HTMLMediaElement::maybeRecordMutedVideoAutoplayOffscreenDuration()
+{
+    if (!m_autoplayOffscreenVisibilityObserver)
+        return;
+
+    double timeDeltaMS = m_mutedVideoAutoplayOffscreenDurationMS;
+    if (timeDeltaMS < 0)
+        timeDeltaMS = 0;
+    if (timeDeltaMS > maxUmaDuration)
+        timeDeltaMS = maxUmaDuration;
+
+    if (m_isAutoplayFromAttribute) {
+        DEFINE_STATIC_LOCAL(CustomCountHistogram, durationHistogram, ("Media.Video.Autoplay.Muted.FromAttribute.OffscreenDuration", 0, maxUmaDuration, umaBucketCount));
+        durationHistogram.count(timeDeltaMS);
+    } else {
+        DEFINE_STATIC_LOCAL(CustomCountHistogram, durationHistogram, ("Media.Video.Autoplay.Muted.FromMethod.OffscreenDuration", 0, maxUmaDuration, umaBucketCount));
+        durationHistogram.count(timeDeltaMS);
+    }
+    m_autoplayOffscreenVisibilityObserver->stop();
+    m_autoplayOffscreenVisibilityObserver = nullptr;
+    m_mutedVideoAutoplayOffscreenDurationMS = 0;
 }
 
 void HTMLMediaElement::clearWeakMembers(Visitor* visitor)