Fix under-invalidation of media buffered ranges

third_party/WebKit/Source/core/html/shadow/MediaControls.cpp

Index: third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
index 8c0f1083541509794c61c292e4bc9b1401602d05..b1e4225af6ddf532d957d49138b9a734a433203f 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControls.cpp
@@ -32,6 +32,7 @@
 #include "core/events/MouseEvent.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLMediaElement.h"
+#include "core/html/TimeRanges.h"
 #include "core/html/track/TextTrackContainer.h"
 #include "core/layout/LayoutTheme.h"
 #include "platform/EventDispatchForbiddenScope.h"
@@ -126,6 +127,7 @@ MediaControls::MediaControls(HTMLMediaElement& mediaElement)
     , m_panelWidthChangedTimer(this, &MediaControls::panelWidthChangedTimerFired)
     , m_panelWidth(0)
     , m_allowHiddenVolumeControls(RuntimeEnabledFeatures::newMediaPlaybackUiEnabled())
+    , m_bufferedRangesPaintInvalidationTimer(this, &MediaControls::bufferedRangesPaintInvalidationTimerFired)
 {
 }
 
@@ -275,7 +277,7 @@ void MediaControls::reset()
     updateCurrentTimeDisplay();
 
     m_timeline->setDuration(duration);
-    m_timeline->setPosition(mediaElement().currentTime());
+    updateTimelinePosition();
 
     updateVolume();
 
@@ -361,7 +363,7 @@ void MediaControls::playbackStarted()
     }
 
     updatePlayState();
-    m_timeline->setPosition(mediaElement().currentTime());
+    updateTimelinePosition();
     updateCurrentTimeDisplay();
 
     startHideMediaControlsTimer();
@@ -369,7 +371,7 @@ void MediaControls::playbackStarted()
 
 void MediaControls::playbackProgressed()
 {
-    m_timeline->setPosition(mediaElement().currentTime());
+    updateTimelinePosition();
     updateCurrentTimeDisplay();
 
     if (shouldHideMediaControls())
@@ -379,7 +381,7 @@ void MediaControls::playbackProgressed()
 void MediaControls::playbackStopped()
 {
     updatePlayState();
-    m_timeline->setPosition(mediaElement().currentTime());
+    updateTimelinePosition();
     updateCurrentTimeDisplay();
     makeOpaque();
 
@@ -394,6 +396,8 @@ void MediaControls::updatePlayState()
     if (m_overlayPlayButton)
         m_overlayPlayButton->updateDisplayType();
     m_playButton->updateDisplayType();
+
+    startOrStopBufferedRangesPaintInvalidationTimer();
 }
 
 void MediaControls::beginScrubbing()
@@ -782,6 +786,48 @@ void MediaControls::networkStateChanged()
     invalidate(m_fullScreenButton);
     invalidate(m_timeline);
     invalidate(m_volumeSlider);
+
+    startOrStopBufferedRangesPaintInvalidationTimer();
+}
+
+void MediaControls::startOrStopBufferedRangesPaintInvalidationTimer()
+{
+    if (m_mediaElement->getNetworkState() == HTMLMediaElement::kNetworkLoading && m_mediaElement->paused()) {
+        updateBufferedRanges();
+        // Start timer to invalidate m_timeline to repaint the buffered ranges when the media is
+        // loading in paused state. In play state, m_timeline will be invalidated on play progresses.
+        if (!m_bufferedRangesPaintInvalidationTimer.isActive())
+            m_bufferedRangesPaintInvalidationTimer.startRepeating(0.5, BLINK_FROM_HERE);
+    } else {
+        m_bufferedRangesPaintInvalidationTimer.stop();
+    }
+}
+
+void MediaControls::updateTimelinePosition()
+{
+    m_timeline->setPosition(mediaElement().currentTime());
+    // Synchronize buffered ranges when the current time changes.
+    updateBufferedRanges();
+};
+
+void MediaControls::updateBufferedRanges()
+{
+    TimeRanges* newBufferedRanges = m_mediaElement->buffered();
+    if (!m_lastBufferedRanges) {
+        if (!newBufferedRanges->length())
+            return;
+    } else if (*m_lastBufferedRanges != *newBufferedRanges) {
+        return;
+    }
+
+    // Invalidate the timeline to repaint the buffered ranges.
+    invalidate(m_timeline);
+    m_lastBufferedRanges = newBufferedRanges->copy();
+}
+
+void MediaControls::bufferedRangesPaintInvalidationTimerFired(TimerBase*)
+{
+    updateBufferedRanges();
 }
 
 DEFINE_TRACE(MediaControls)
@@ -802,6 +848,7 @@ DEFINE_TRACE(MediaControls)
     visitor->trace(m_textTrackList);
     visitor->trace(m_castButton);
     visitor->trace(m_overlayCastButton);
+    visitor->trace(m_lastBufferedRanges);
     HTMLDivElement::trace(visitor);
 }