Fix under-invalidation of media buffered ranges

third_party/WebKit/Source/core/paint/MediaControlsPainter.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 13 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "core/paint/MediaControlsPainter.h"
 
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
 #include "core/html/HTMLMediaElement.h"
 #include "core/html/TimeRanges.h"
 #include "core/html/shadow/MediaControlElementTypes.h"
+#include "core/html/shadow/MediaControls.h"
 #include "core/paint/PaintInfo.h"
 #include "core/style/ComputedStyle.h"
 #include "platform/graphics/Gradient.h"
 #include "platform/graphics/GraphicsContext.h"
 
 namespace blink {
 
 static const double kCurrentTimeBufferedDelta = 1.0;
 
 typedef WTF::HashMap<const char*, Image*> MediaControlImageMap;
@@ skipping 274 matching lines @@
 
     // Paint the slider bar in the "no data buffered" state.
     Color sliderBackgroundColor;
     if (!useNewUi)
         sliderBackgroundColor = Color(11, 11, 11);
     else
         sliderBackgroundColor = Color(0xda, 0xda, 0xda);
 
     paintRoundedSliderBackground(rect, style, context, sliderBackgroundColor);
 
+    TimeRanges* bufferedTimeRanges = mediaElement->mediaControls()->bufferedRangesForPainting();

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

could one use mediaElement->buffered() here as well?  the buffered copy could be
half a second stale.

or, am i just missing something subtle (or obvious :) )?

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

This is required in the under-invalidation checking mode (for testing only) if
we enable caching of MediaSliderPart. In the mode, we force repainting any
object even it's not invalidated, and any changed painting must have been
invalidated. Using buffered() here will break the requirement.

However, using buffered() won't cause any real problem because in we only
repaint an object when it's invalidated.

Reverted changes in this file, and disable caching in under-invalidation
checking mode instead. 

+    if (!bufferedTimeRanges)
+        return;
+
     // Draw the buffered range. Since the element may have multiple buffered ranges and it'd be
     // distracting/'busy' to show all of them, show only the buffered range containing the current play head.
-    TimeRanges* bufferedTimeRanges = mediaElement->buffered();
     float duration = mediaElement->duration();
     float currentTime = mediaElement->currentTime();
     if (std::isnan(duration) || std::isinf(duration) || !duration || std::isnan(currentTime))
         return;
 
     for (unsigned i = 0; i < bufferedTimeRanges->length(); ++i) {
         float start = bufferedTimeRanges->start(i, ASSERT_NO_EXCEPTION);
         float end = bufferedTimeRanges->end(i, ASSERT_NO_EXCEPTION);
         // The delta is there to avoid corner cases when buffered
         // ranges is out of sync with current time because of
@@ skipping 291 matching lines @@
     }
 
     float zoomLevel = style.effectiveZoom();
     if (thumbImage) {
         style.setWidth(Length(static_cast<int>(width * zoomLevel), Fixed));
         style.setHeight(Length(static_cast<int>(height * zoomLevel), Fixed));
     }
 }
 
 } // namespace blink