k-rate playbackRate and detune reaches final value

third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp

Index: third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp b/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
index dbb6a1b8defe27a58eb4ce5f9b3cb4d60a898c33..eacec0b72c9e5da2a8b148736bbf19764fd6f25f 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
@@ -857,7 +857,15 @@ float AudioParamTimeline::valuesForFrameRangeImpl(size_t startFrame,
     // "forever".  SetValueCurve also has an explicit SetValue at the end of
     // the curve, so we don't need to worry that SetValueCurve time is a
     // start time, not an end time.
-    if (lastEventTime < currentTime && lastEventType != ParamEvent::SetTarget) {
+    //
+    // Allow at least one render quantum to go by before handling this
+    // to allow k-rate parameters to finish processing the event. See
+    // crbug.com/672857. Due to possible roundoff, arbirtrarily wait
+    // for 1.5 render quanta instead of 1.

[hongchan, 2017/01/12 23:32:16]

What is the possible side effect of waiting 1.5 RQ?

[Raymond Toy, 2017/01/12 23:49:10]

I think the only side-effect would be that we now end up clearing the event list
after 2 RQ after the last event instead of immediately. I think it's useful to
be able to empty the event list so that we can do the fast path if no events are
added again.

+    if (lastEventTime +
+                1.5 * AudioUtilities::kRenderQuantumFrames / sampleRate <
+            currentTime &&
+        lastEventType != ParamEvent::SetTarget) {

[hongchan, 2017/01/12 23:32:15]

Wow. Is this what 'git cl format' offers? Could you please confirm it?

[Raymond Toy, 2017/01/12 23:46:51]

Yep.  This isn't how I had originally indented it. I tried again and put
everything on one line, and git cl format produces this again.

       // The event has finished, so just copy the default value out.
       // Since all events are now also in the past, we can just remove all
       // timeline events too because |defaultValue| has the expected