Paint buffered range closest to the current play position

Source/core/layout/LayoutMediaControls.cpp

 /*
  * Copyright (C) 2009 Apple Inc.
  * Copyright (C) 2009 Google Inc.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 21 matching lines @@
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/TimeRanges.h"
 #include "core/layout/PaintInfo.h"
 #include "platform/graphics/Gradient.h"
 #include "platform/graphics/GraphicsContext.h"
 
 namespace blink {
 
 typedef WTF::HashMap<const char*, Image*> MediaControlImageMap;
 static MediaControlImageMap* gMediaControlImageMap = 0;
+static double kCurrentTimeBufferedDelta = 1.0;
 
 static Image* platformResource(const char* name)
 {
     if (!gMediaControlImageMap)
         gMediaControlImageMap = new MediaControlImageMap();
     if (Image* image = gMediaControlImageMap->get(name))
         return image;
     if (Image* image = Image::loadPlatformResource(name).leakRef()) {
         gMediaControlImageMap->set(name, image);
         return image;
@@ skipping 156 matching lines @@
     // distracting/'busy' to show all of them, show only the buffered range containing the current play head.
     RefPtrWillBeRawPtr<TimeRanges> bufferedTimeRanges = mediaElement->buffered();
     float duration = mediaElement->duration();
     float currentTime = mediaElement->currentTime();
     if (std::isnan(duration) || std::isinf(duration) || !duration || std::isnan(currentTime))
         return true;
 
     for (unsigned i = 0; i < bufferedTimeRanges->length(); ++i) {
         float start = bufferedTimeRanges->start(i, ASSERT_NO_EXCEPTION);
         float end = bufferedTimeRanges->end(i, ASSERT_NO_EXCEPTION);
-        if (std::isnan(start) || std::isnan(end) || start > currentTime || end < currentTime)
+        // The delta is there to avoid corner cases when buffered
+        // ranges is out of sync with current time because of
+        // asynchronous media pipeline and current time caching in
+        // HTMLMediaElement.
+        // This is related to https://www.w3.org/Bugs/Public/show_bug.cgi?id=28125
+        // FIXME: Remove this workaround when WebMediaPlayer
+        // has an asynchronous pause interface.
+        if (std::isnan(start) || std::isnan(end)
+            || start > currentTime + kCurrentTimeBufferedDelta || end < currentTime)
             continue;
         int startPosition = int(start * rect.width() / duration);
         int currentPosition = int(currentTime * rect.width() / duration);
         int endPosition = int(end * rect.width() / duration);
 
         // Add half the thumb width proportionally adjusted to the current painting position.
         int thumbCenter = mediaSliderThumbWidth / 2;
         int addWidth = thumbCenter * (1.0 - 2.0 * currentPosition / rect.width());
         currentPosition += addWidth;
 
@@ skipping 237 matching lines @@
 {
     return formatChromiumMediaControlsTime(time, time);
 }
 
 String LayoutMediaControls::formatMediaControlsCurrentTime(float currentTime, float duration)
 {
     return formatChromiumMediaControlsTime(currentTime, duration);
 }
 
 } // namespace blink