Fix under-invalidation of media buffered ranges

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

Index: third_party/WebKit/Source/core/html/shadow/MediaControls.h
diff --git a/third_party/WebKit/Source/core/html/shadow/MediaControls.h b/third_party/WebKit/Source/core/html/shadow/MediaControls.h
index 8b5892229a9919dc173917c16384231f1a0d6e78..d660f5c93f53f2c7bc2da682c10685c5d65e5821 100644
--- a/third_party/WebKit/Source/core/html/shadow/MediaControls.h
+++ b/third_party/WebKit/Source/core/html/shadow/MediaControls.h
@@ -34,6 +34,7 @@ namespace blink {
 
 class Event;
 class TextTrackContainer;
+class TimeRanges;
 
 class CORE_EXPORT MediaControls final : public HTMLDivElement {
 public:
@@ -86,6 +87,10 @@ public:
     // Notify us that the media element's network state has changed.
     void networkStateChanged();
 
+    // Returns the cached buffered ranges for painting updated by the m_bufferedRangesPaintInvalidationTimer
+    // periodically while the media is loading. It can be null.
+    TimeRanges* bufferedRangesForPainting() const { return m_bufferedRangesForPainting.get(); }
+
     DECLARE_VIRTUAL_TRACE();
 
 private:
@@ -127,6 +132,10 @@ private:
     void defaultEventHandler(Event*) override;
     bool containsRelatedTarget(Event*);
 
+    void updateTimelinePosition();
+    void updateBufferedRanges();
+    void bufferedRangesPaintInvalidationTimerFired(TimerBase*);
+
     Member<HTMLMediaElement> m_mediaElement;
 
     // Media control elements.
@@ -155,6 +164,9 @@ private:
     int m_panelWidth;
 
     bool m_allowHiddenVolumeControls : 1;
+
+    Timer<MediaControls> m_bufferedRangesPaintInvalidationTimer;
+    Member<TimeRanges> m_bufferedRangesForPainting;
 };
 
 DEFINE_ELEMENT_TYPE_CASTS(MediaControls, isMediaControls());