[MSE] Round SourceBuffer removal range

https://bugs.webkit.org/show_bug.cgi?id=245081

Reviewed by Xabier Rodriguez-Calvar.

Representation of removal times as double in SourceBuffer::remove() can cause
problems in HBOMax due to precision/rounding problems.

In some problematic cases an unintended frame would be marked for removal because
of the very small overlap that could come from precision lost. For instance,
HBOMax uses the PTS of the next sample as removal 'end' and unexpectedly removes
the next segment (as it's a sync frame) sometimes.

Rounding the double removal range delimiters to nanoseconds would help to avoid
those problematic cases.

Original author: Andrzej Surdej <Andrzej_Surdej@comcast.com>
See: WebPlatformForEmbedded/WPEWebKit#921

* Source/WebCore/Modules/mediasource/SourceBuffer.cpp:
(WebCore::SourceBuffer::remove): Round the removal range start/end values to millisecond precision.

Canonical link: https://commits.webkit.org/254472@main

Source/WebCore/Modules/mediasource/SourceBuffer.cpp

@@ -282,7 +282,9 @@ ExceptionOr<void> SourceBuffer::abort()
 
 ExceptionOr<void> SourceBuffer::remove(double start, double end)
 {
-    return remove(MediaTime::createWithDouble(start), MediaTime::createWithDouble(end));
+    // Limit timescale to 1/1000 of microsecond so samples won't accidentally overlap with removal range by precision lost (e.g. by 0.000000000000X [sec]).
+    static const uint32_t timescale = 1000000000;
+    return remove(MediaTime::createWithDouble(start, timescale), MediaTime::createWithDouble(end, timescale));
 }
 
 ExceptionOr<void> SourceBuffer::remove(const MediaTime& start, const MediaTime& end)