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..0309e76b2985a0415a3fe7fb52b6aa8bc7aad9fd 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();
 
@@ -774,6 +776,8 @@ void MediaControls::invalidate(Element* element)
         layoutObject->setShouldDoFullPaintInvalidation();
 }
 
+static const double kBufferedRangesPaintInvalidationInterval = 0.5;
+
 void MediaControls::networkStateChanged()
 {
     invalidate(m_playButton);
@@ -782,6 +786,40 @@ void MediaControls::networkStateChanged()
     invalidate(m_fullScreenButton);
     invalidate(m_timeline);
     invalidate(m_volumeSlider);
+
+    updateBufferedRanges();
+    if (m_mediaElement->getNetworkState() == HTMLMediaElement::kNetworkLoading) {
+        if (!m_bufferedRangesPaintInvalidationTimer.isActive())
+            m_bufferedRangesPaintInvalidationTimer.startRepeating(kBufferedRangesPaintInvalidationInterval, BLINK_FROM_HERE);
+    } else {
+        m_bufferedRangesPaintInvalidationTimer.stop();
+    }
+}
+
+void MediaControls::updateTimelinePosition()
+{
+    m_timeline->setPosition(mediaElement().currentTime());
+    // Synchronize buffered ranges when the current time change.
+    updateBufferedRanges();
+}
+
+void MediaControls::updateBufferedRanges()
+{
+    TimeRanges* newBuffered = m_mediaElement->buffered();
+    if (!m_bufferedRangesForPainting) {
+        if (!newBuffered->length())
+            return;
+    } else if (*m_bufferedRangesForPainting == *newBuffered) {

[liberato (no reviews please), 2016/08/29 15:25:34]

might one just unconditionally invalidate the timeline, and avoid the complexity
of buffering and checking for equality?

or, to put it another way, how many invalidations does this actually save?  it's
only the timer case that it matters; setPosition via updateTimelinePosition
always invalidates anyway, i think.

[Xianzhu, 2016/08/29 18:04:14]

Good question. It's unlikely to save invalidations using the comparison. Changed
to unconditional. Along with the change in MediaControlsPainter, the CL is much
simplified.

+        return;
+    }
+
+    m_bufferedRangesForPainting = newBuffered;
+    invalidate(m_timeline);
+}
+
+void MediaControls::bufferedRangesPaintInvalidationTimerFired(TimerBase*)
+{
+    updateBufferedRanges();
 }
 
 DEFINE_TRACE(MediaControls)
@@ -802,6 +840,7 @@ DEFINE_TRACE(MediaControls)
     visitor->trace(m_textTrackList);
     visitor->trace(m_castButton);
     visitor->trace(m_overlayCastButton);
+    visitor->trace(m_bufferedRangesForPainting);
     HTMLDivElement::trace(visitor);
 }