Monitor the intersection of video and viewport.

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 72ab6fe5645646c002559684f5da5634e1bf8242..b1bbf1741e39304b8c485d49b5a2373f57c6d0f8 100644
--- a/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
+++ b/third_party/WebKit/Source/core/html/AutoplayUmaHelper.cpp
@@ -30,11 +30,9 @@ AutoplayUmaHelper::AutoplayUmaHelper(HTMLMediaElement* element)
     : EventListener(CPPEventListenerType),
       m_source(AutoplaySource::NumberOfSources),
       m_element(element),
-      m_mutedVideoPlayMethodVisibilityObserver(nullptr),
       m_mutedVideoAutoplayOffscreenStartTimeMS(0),
       m_mutedVideoAutoplayOffscreenDurationMS(0),
-      m_isVisible(false),
-      m_mutedVideoOffscreenDurationVisibilityObserver(nullptr) {}
+      m_isVisible(false) {}
 
 AutoplayUmaHelper::~AutoplayUmaHelper() = default;
 
@@ -116,28 +114,22 @@ void AutoplayUmaHelper::didMoveToNewDocument(Document& oldDocument) {
                                                         this, false);
 }
 
-void AutoplayUmaHelper::onVisibilityChangedForMutedVideoPlayMethodBecomeVisible(
-    bool isVisible) {
-  if (!isVisible || !m_mutedVideoPlayMethodVisibilityObserver)
-    return;
-
-  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());
+void AutoplayUmaHelper::visibilityMightChangedforMutedVideo(bool isVisible) {
+  if (m_isObservingVisibilityOfMutedVideoOffscreenDuration && isVisible)

[miu, 2016/11/09 22:02:08]

Note: This method is going to be called from HTMLMediaElement repeatedly for the
same |isVisible| value. That never happened before. Therefore, I think you
should add to the top of this method:

  if (isVisible == m_isVisible)
    return;
  m_isVisible = isVisible;

...and update the code in the last if-statement of this method: It doesn't need
the same check, and doesn't need to assign to m_isVisible.

[xjz, 2016/11/11 01:07:29]

Done.

+    maybeStopRecordingMutedVideoPlayMethodBecomeVisible(true);
 
-  m_isVisible = isVisible;
+  if (m_isObservingVisibilityOfMutedVideoOffscreenDuration &&
+      isVisible != m_isVisible) {
+    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,
@@ -173,12 +165,7 @@ void AutoplayUmaHelper::maybeStartRecordingMutedVideoPlayMethodBecomeVisible() {
       !m_element->muted())
     return;
 
-  m_mutedVideoPlayMethodVisibilityObserver = new ElementVisibilityObserver(
-      m_element,
-      WTF::bind(&AutoplayUmaHelper::
-                    onVisibilityChangedForMutedVideoPlayMethodBecomeVisible,
-                wrapWeakPersistent(this)));
-  m_mutedVideoPlayMethodVisibilityObserver->start();
+  m_isObservingVisibilityOfMutedAutoplayVideo = true;
   if (m_element->document().domWindow())
     m_element->document().domWindow()->addEventListener(EventTypeNames::unload,
                                                         this, false);
@@ -186,15 +173,14 @@ void AutoplayUmaHelper::maybeStartRecordingMutedVideoPlayMethodBecomeVisible() {
 
 void AutoplayUmaHelper::maybeStopRecordingMutedVideoPlayMethodBecomeVisible(
     bool visible) {
-  if (!m_mutedVideoPlayMethodVisibilityObserver)
+  if (!m_isObservingVisibilityOfMutedAutoplayVideo)
     return;
 
   DEFINE_STATIC_LOCAL(BooleanHistogram, histogram,
                       ("Media.Video.Autoplay.Muted.PlayMethod.BecomesVisible"));
 
   histogram.count(visible);
-  m_mutedVideoPlayMethodVisibilityObserver->stop();
-  m_mutedVideoPlayMethodVisibilityObserver = nullptr;
+  m_isObservingVisibilityOfMutedAutoplayVideo = false;
   maybeUnregisterUnloadListener();
 }
 
@@ -206,13 +192,7 @@ void AutoplayUmaHelper::maybeStartRecordingMutedVideoOffscreenDuration() {
   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_isObservingVisibilityOfMutedVideoOffscreenDuration = true;
   m_element->addEventListener(EventTypeNames::pause, this, false);
   if (m_element->document().domWindow())
     m_element->document().domWindow()->addEventListener(EventTypeNames::unload,
@@ -220,7 +200,7 @@ void AutoplayUmaHelper::maybeStartRecordingMutedVideoOffscreenDuration() {
 }
 
 void AutoplayUmaHelper::maybeStopRecordingMutedVideoOffscreenDuration() {
-  if (!m_mutedVideoOffscreenDurationVisibilityObserver)
+  if (!m_isObservingVisibilityOfMutedVideoOffscreenDuration)
     return;
 
   if (!m_isVisible)
@@ -247,8 +227,7 @@ void AutoplayUmaHelper::maybeStopRecordingMutedVideoOffscreenDuration() {
          maxOffscreenDurationUmaMS, offscreenDurationUmaBucketCount));
     durationHistogram.count(boundedTime);
   }
-  m_mutedVideoOffscreenDurationVisibilityObserver->stop();
-  m_mutedVideoOffscreenDurationVisibilityObserver = nullptr;
+  m_isObservingVisibilityOfMutedVideoOffscreenDuration = false;
   m_mutedVideoAutoplayOffscreenDurationMS = 0;
   m_element->removeEventListener(EventTypeNames::pause, this, false);
   maybeUnregisterUnloadListener();
@@ -261,15 +240,13 @@ void AutoplayUmaHelper::maybeUnregisterUnloadListener() {
 }
 
 bool AutoplayUmaHelper::shouldListenToUnloadEvent() const {
-  return m_mutedVideoPlayMethodVisibilityObserver ||
-         m_mutedVideoOffscreenDurationVisibilityObserver;
+  return m_isObservingVisibilityOfMutedAutoplayVideo ||
+         m_isObservingVisibilityOfMutedVideoOffscreenDuration;
 }
 
 DEFINE_TRACE(AutoplayUmaHelper) {
   EventListener::trace(visitor);
   visitor->trace(m_element);
-  visitor->trace(m_mutedVideoPlayMethodVisibilityObserver);
-  visitor->trace(m_mutedVideoOffscreenDurationVisibilityObserver);
 }
 
 }  // namespace blink