Detect change on video/viewport intersection when rendered remotely

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 9e4d7251251f3d24dc3bbe4989ba190af632954f..e7c49862abaa72e0e9f91965e381361bc16dbcc6 100644
--- a/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLMediaElement.cpp
@@ -128,6 +128,7 @@ namespace {
 
 constexpr float kMostlyFillViewportThreshold = 0.85f;
 constexpr double kMostlyFillViewportBecomeStableSeconds = 5;
+constexpr double kCheckViewportIntersectionIntervalSeconds = 1;
 
 enum MediaControlsShow {
   MediaControlsShowAttribute = 0,
@@ -370,6 +371,9 @@ HTMLMediaElement::HTMLMediaElement(const QualifiedName& tagName,
       m_viewportFillDebouncerTimer(
           this,
           &HTMLMediaElement::viewportFillDebouncerTimerFired),
+      m_checkViewportIntersectionTimer(
+          this,
+          &HTMLMediaElement::checkViewportIntersectionTimerFired),
       m_playedTimeRanges(),
       m_asyncEventQueue(GenericEventQueue::create(this)),
       m_playbackRate(1.0f),
@@ -2462,8 +2466,6 @@ void HTMLMediaElement::startPlaybackProgressTimer() {
 }
 
 void HTMLMediaElement::playbackProgressTimerFired(TimerBase*) {
-  checkViewportIntersectionChanged();
-
   if (!std::isnan(m_fragmentEndTime) && currentTime() >= m_fragmentEndTime &&
       getDirectionOfPlayback() == Forward) {
     m_fragmentEndTime = std::numeric_limits<double>::quiet_NaN();
@@ -3302,6 +3304,7 @@ void HTMLMediaElement::updatePlayState() {
 void HTMLMediaElement::stopPeriodicTimers() {
   m_progressEventTimer.stop();
   m_playbackProgressTimer.stop();
+  m_checkViewportIntersectionTimer.stop();
 }
 
 void HTMLMediaElement::
@@ -4062,9 +4065,16 @@ DEFINE_TRACE(HTMLMediaElement::AudioSourceProviderImpl) {
   visitor->trace(m_client);
 }
 
-void HTMLMediaElement::checkViewportIntersectionChanged() {
-  // TODO(xjz): Early return if we not in tab mirroring.
+void HTMLMediaElement::activateViewportIntersectionMonitoring(bool activate) {
+  if (activate && !m_checkViewportIntersectionTimer.isActive()) {
+    m_checkViewportIntersectionTimer.startRepeating(
+        kCheckViewportIntersectionIntervalSeconds, BLINK_FROM_HERE);
+  } else if (!activate) {
+    m_checkViewportIntersectionTimer.stop();
+  }
+}
 
+void HTMLMediaElement::checkViewportIntersectionTimerFired(TimerBase*) {
   bool shouldReportRootBounds = true;
   IntersectionGeometry geometry(nullptr, *this, Vector<Length>(),
                                 shouldReportRootBounds);