Reland "Record the offscreen playing duration of autoplaying muted videos"

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

Index: third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
diff --git a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
index 50e0091a8a0dd77bb29aee80af1bf0bf1be7f354..4f3887add4e659264c3b878f32ebc3748599f5ff 100644
--- a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
@@ -11,16 +11,14 @@
 #include "core/frame/Settings.h"
 #include "core/html/HTMLMediaElement.h"
 #include "platform/Histogram.h"
+#include "wtf/CurrentTime.h"
 
 namespace blink {
 
 namespace {
 
-void recordVideoAutoplayMutedPlayMethodBecomesVisibleUma(bool visible)
-{
-    DEFINE_STATIC_LOCAL(BooleanHistogram, histogram, ("Media.Video.Autoplay.Muted.PlayMethod.BecomesVisible"));
-    histogram.count(visible);
-}
+const int32_t maxOffscreenDurationUmaMS = 60 * 60 * 1000;
+const int32_t offscreenDurationUmaBucketCount = 50;
 
 } // namespace
 
@@ -33,7 +31,11 @@ AutoplayUmaHelper::AutoplayUmaHelper(HTMLMediaElement* element)
     : EventListener(CPPEventListenerType)
     , m_source(AutoplaySource::NumberOfSources)
     , m_element(element)
-    , m_videoMutedPlayMethodVisibilityObserver(nullptr) { }
+    , m_mutedVideoPlayMethodVisibilityObserver(nullptr)
+    , m_mutedVideoAutoplayOffscreenStartTimeMS(0)
+    , m_mutedVideoAutoplayOffscreenDurationMS(0)
+    , m_isVisible(false)
+    , m_mutedVideoOffscreenDurationVisibilityObserver(nullptr) { }
 
 AutoplayUmaHelper::~AutoplayUmaHelper() = default;
 
@@ -49,6 +51,11 @@ void AutoplayUmaHelper::onAutoplayInitiated(AutoplaySource source)
     DEFINE_STATIC_LOCAL(EnumerationHistogram, audioHistogram, ("Media.Audio.Autoplay", static_cast<int>(AutoplaySource::NumberOfSources)));
     DEFINE_STATIC_LOCAL(EnumerationHistogram, blockedMutedVideoHistogram, ("Media.Video.Autoplay.Muted.Blocked", AutoplayBlockedReasonMax));
 
+    // Autoplay already initiated
+    // TODO(zqzhang): how about having autoplay attribute and calling `play()` in the script?
+    if (m_source != AutoplaySource::NumberOfSources)
+        return;
+
     m_source = source;
 
     // Record the source.
@@ -74,8 +81,7 @@ void AutoplayUmaHelper::onAutoplayInitiated(AutoplaySource source)
         }
     }
 
-    if (m_source == AutoplaySource::Method && m_element->isHTMLVideoElement() && m_element->muted())
-        m_element->addEventListener(EventTypeNames::playing, this, false);
+    m_element->addEventListener(EventTypeNames::playing, this, false);
 }
 
 void AutoplayUmaHelper::recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus status)
@@ -87,7 +93,7 @@ void AutoplayUmaHelper::recordAutoplayUnmuteStatus(AutoplayUnmuteActionStatus st
 
 void AutoplayUmaHelper::didMoveToNewDocument(Document& oldDocument)
 {
-    if (!m_videoMutedPlayMethodVisibilityObserver)
+    if (!shouldListenToUnloadEvent())
         return;
 
     if (oldDocument.domWindow())
@@ -96,57 +102,139 @@ void AutoplayUmaHelper::didMoveToNewDocument(Document& oldDocument)
         m_element->document().domWindow()->addEventListener(EventTypeNames::unload, this, false);
 }
 
-void AutoplayUmaHelper::onVisibilityChangedForVideoMutedPlayMethod(bool isVisible)
+void AutoplayUmaHelper::onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(bool isVisible)
 {
-    if (!isVisible || !m_videoMutedPlayMethodVisibilityObserver)
+    if (!isVisible || !m_mutedVideoPlayMethodVisibilityObserver)
         return;
 
-    recordVideoAutoplayMutedPlayMethodBecomesVisibleUma(true);
-    m_videoMutedPlayMethodVisibilityObserver->stop();
-    m_videoMutedPlayMethodVisibilityObserver = nullptr;
-    if (m_element && m_element->document().domWindow())
-        m_element->document().domWindow()->removeEventListener(EventTypeNames::unload, this, false);
+    maybeStopRecordingMutedVideoPlayMethodBecomeVisible(true);
+}
+
+void AutoplayUmaHelper::onVisibilityChangedForMutedVideoOffscreenDuration(bool isVisible)
+{
+    if (isVisible == m_isVisible)
+        return;
+
+    if (isVisible)
+        m_mutedVideoAutoplayOffscreenDurationMS += static_cast<int64_t>(monotonicallyIncreasingTimeMS()) - m_mutedVideoAutoplayOffscreenStartTimeMS;
+    else
+        m_mutedVideoAutoplayOffscreenStartTimeMS = static_cast<int64_t>(monotonicallyIncreasingTimeMS());
+
+    m_isVisible = isVisible;
 }
 
 void AutoplayUmaHelper::handleEvent(ExecutionContext* executionContext, Event* event)
 {
     if (event->type() == EventTypeNames::playing)
         handlePlayingEvent();
+    else if (event->type() == EventTypeNames::pause)
+        handlePauseEvent();
     else if (event->type() == EventTypeNames::unload)
         handleUnloadEvent();
     else
         NOTREACHED();
 }
 
+void AutoplayUmaHelper::handlePlayingEvent()
+{
+    maybeStartRecordingMutedVideoPlayMethodBecomeVisible();
+    maybeStartRecordingMutedVideoOffscreenDuration();
+
+    m_element->removeEventListener(EventTypeNames::playing, this, false);
+}
+
+void AutoplayUmaHelper::handlePauseEvent()
+{
+    maybeStopRecordingMutedVideoOffscreenDuration();
+}
+
 void AutoplayUmaHelper::handleUnloadEvent()
 {
-    if (m_videoMutedPlayMethodVisibilityObserver) {
-        recordVideoAutoplayMutedPlayMethodBecomesVisibleUma(false);
-        m_videoMutedPlayMethodVisibilityObserver->stop();
-        m_videoMutedPlayMethodVisibilityObserver = nullptr;
-        if (m_element && m_element->document().domWindow())
-            m_element->document().domWindow()->removeEventListener(EventTypeNames::unload, this, false);
-    }
+    maybeStopRecordingMutedVideoPlayMethodBecomeVisible(false);
+    maybeStopRecordingMutedVideoOffscreenDuration();
 }
 
-void AutoplayUmaHelper::handlePlayingEvent()
+void AutoplayUmaHelper::maybeStartRecordingMutedVideoPlayMethodBecomeVisible()
 {
-    if (m_source == AutoplaySource::Method && m_element->isHTMLVideoElement() && m_element->muted()) {
-        if (!m_videoMutedPlayMethodVisibilityObserver) {
-            m_videoMutedPlayMethodVisibilityObserver = new ElementVisibilityObserver(m_element, WTF::bind(&AutoplayUmaHelper::onVisibilityChangedForVideoMutedPlayMethod, wrapWeakPersistent(this)));
-            m_videoMutedPlayMethodVisibilityObserver->start();
-            if (m_element && m_element->document().domWindow())
-                m_element->document().domWindow()->addEventListener(EventTypeNames::unload, this, false);
-        }
+    if (m_source != AutoplaySource::Method || !m_element->isHTMLVideoElement() || !m_element->muted())
+        return;
+
+    m_mutedVideoPlayMethodVisibilityObserver = new ElementVisibilityObserver(m_element, WTF::bind(&AutoplayUmaHelper::onVisibilityChangedForMutedVideoPlayMethodBecomeVisible, wrapWeakPersistent(this)));
+    m_mutedVideoPlayMethodVisibilityObserver->start();
+    if (m_element->document().domWindow())
+        m_element->document().domWindow()->addEventListener(EventTypeNames::unload, this, false);
+}
+
+void AutoplayUmaHelper::maybeStopRecordingMutedVideoPlayMethodBecomeVisible(bool visible)
+{
+    if (!m_mutedVideoPlayMethodVisibilityObserver)
+        return;
+
+    DEFINE_STATIC_LOCAL(BooleanHistogram, histogram, ("Media.Video.Autoplay.Muted.PlayMethod.BecomesVisible"));
+
+    histogram.count(visible);
+    m_mutedVideoPlayMethodVisibilityObserver->stop();
+    m_mutedVideoPlayMethodVisibilityObserver = nullptr;
+    maybeUnregisterUnloadListener();
+}
+
+void AutoplayUmaHelper::maybeStartRecordingMutedVideoOffscreenDuration()
+{
+    if (!m_element->isHTMLVideoElement() || !m_element->muted())
+        return;
+
+    // Start recording muted video playing offscreen duration.
+    m_mutedVideoAutoplayOffscreenStartTimeMS = static_cast<int64_t>(monotonicallyIncreasingTimeMS());
+    m_isVisible = false;
+    m_mutedVideoOffscreenDurationVisibilityObserver = new ElementVisibilityObserver(m_element, WTF::bind(&AutoplayUmaHelper::onVisibilityChangedForMutedVideoOffscreenDuration, wrapWeakPersistent(this)));
+    m_mutedVideoOffscreenDurationVisibilityObserver->start();
+    m_element->addEventListener(EventTypeNames::pause, this, false);
+    if (m_element->document().domWindow())
+        m_element->document().domWindow()->addEventListener(EventTypeNames::unload, this, false);
+}
+
+void AutoplayUmaHelper::maybeStopRecordingMutedVideoOffscreenDuration()
+{
+    if (!m_mutedVideoOffscreenDurationVisibilityObserver)
+        return;
+
+    if (!m_isVisible)
+        m_mutedVideoAutoplayOffscreenDurationMS += static_cast<int64_t>(monotonicallyIncreasingTimeMS()) - m_mutedVideoAutoplayOffscreenStartTimeMS;
+
+    // Since histograms uses int32_t, the duration needs to be limited to std::numeric_limits<int32_t>::max().
+    int32_t boundedTime = static_cast<int32_t>(std::min<int64_t>(m_mutedVideoAutoplayOffscreenDurationMS, std::numeric_limits<int32_t>::max()));
+
+    if (m_source == AutoplaySource::Attribute) {
+        DEFINE_STATIC_LOCAL(CustomCountHistogram, durationHistogram, ("Media.Video.Autoplay.Muted.Attribute.OffscreenDuration", 1, maxOffscreenDurationUmaMS, offscreenDurationUmaBucketCount));
+        durationHistogram.count(boundedTime);
+    } else {
+        DEFINE_STATIC_LOCAL(CustomCountHistogram, durationHistogram, ("Media.Video.Autoplay.Muted.PlayMethod.OffscreenDuration", 1, maxOffscreenDurationUmaMS, offscreenDurationUmaBucketCount));
+        durationHistogram.count(boundedTime);
     }
-    m_element->removeEventListener(EventTypeNames::playing, this, false);
+    m_mutedVideoOffscreenDurationVisibilityObserver->stop();
+    m_mutedVideoOffscreenDurationVisibilityObserver = nullptr;
+    m_mutedVideoAutoplayOffscreenDurationMS = 0;
+    m_element->removeEventListener(EventTypeNames::pause, this, false);
+    maybeUnregisterUnloadListener();
+}
+
+void AutoplayUmaHelper::maybeUnregisterUnloadListener()
+{
+    if (!shouldListenToUnloadEvent() && m_element && m_element->document().domWindow())
+        m_element->document().domWindow()->removeEventListener(EventTypeNames::unload, this, false);
+}
+
+bool AutoplayUmaHelper::shouldListenToUnloadEvent() const
+{
+    return m_mutedVideoPlayMethodVisibilityObserver || m_mutedVideoOffscreenDurationVisibilityObserver;
 }
 
 DEFINE_TRACE(AutoplayUmaHelper)
 {
     EventListener::trace(visitor);
     visitor->trace(m_element);
-    visitor->trace(m_videoMutedPlayMethodVisibilityObserver);
+    visitor->trace(m_mutedVideoPlayMethodVisibilityObserver);
+    visitor->trace(m_mutedVideoOffscreenDurationVisibilityObserver);
 }
 
 } // namespace blink