Clamp AudioParam automations to the nominal range.

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 85ee0a196b442aba014fa2485fb74cea182f3525..804538f4b180589659861bd69a8d2dfcc24321a2 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
@@ -337,7 +337,7 @@ void AudioParamTimeline::cancelScheduledValues(double startTime, ExceptionState&
     }
 }
 
-float AudioParamTimeline::valueForContextTime(AudioDestinationHandler& audioDestination, float defaultValue, bool& hasValue)
+float AudioParamTimeline::valueForContextTime(AudioDestinationHandler& audioDestination, float defaultValue, bool& hasValue, float minValue, float maxValue)
 {
     {
         MutexTryLocker tryLocker(m_eventsLock);
@@ -352,7 +352,7 @@ float AudioParamTimeline::valueForContextTime(AudioDestinationHandler& audioDest
     double sampleRate = audioDestination.sampleRate();
     size_t startFrame = audioDestination.currentSampleFrame();
     double controlRate = sampleRate / AudioHandler::ProcessingSizeInFrames; // one parameter change per render quantum
-    value = valuesForFrameRange(startFrame, startFrame + 1, defaultValue, &value, 1, sampleRate, controlRate);
+    value = valuesForFrameRange(startFrame, startFrame + 1, defaultValue, &value, 1, sampleRate, controlRate, minValue, maxValue);
 
     hasValue = true;
     return value;
@@ -365,7 +365,9 @@ float AudioParamTimeline::valuesForFrameRange(
     float* values,
     unsigned numberOfValues,
     double sampleRate,
-    double controlRate)
+    double controlRate,
+    float minValue,
+    float maxValue)
 {
     // We can't contend the lock in the realtime audio thread.
     MutexTryLocker tryLocker(m_eventsLock);
@@ -377,7 +379,13 @@ float AudioParamTimeline::valuesForFrameRange(
         return defaultValue;
     }

[hongchan, 2016/06/17 17:00:40]

Sorry to bring this up again, why this pattern is different form the line
342~348? This mutex is active until this method is finished.

[Raymond Toy, 2016/06/17 17:10:05]

I didn't actually change this.  Are you saying I should?

[hongchan, 2016/06/17 17:55:06]

Disregard my comment. They are different, but looks okay here.

 
-    return valuesForFrameRangeImpl(startFrame, endFrame, defaultValue, values, numberOfValues, sampleRate, controlRate);
+    float lastValue = valuesForFrameRangeImpl(startFrame, endFrame, defaultValue, values, numberOfValues, sampleRate, controlRate);
+
+    // Clamp the values now to the nominal range
+    for (unsigned k = 0; k < numberOfValues; ++k)
+        values[k] = clampTo(values[k], minValue, maxValue);
+
+    return lastValue;

[hongchan, 2016/06/17 17:00:40]

Are these safe outside of tryLock?

[Raymond Toy, 2016/06/17 17:10:05]

I didn't really change the thread safety here.  It should be as safe (or unsafe)
as before.

[hongchan, 2016/06/17 17:55:06]

I misundstood the scope of tryLock. This looks safe.

 }
 
 float AudioParamTimeline::valuesForFrameRangeImpl(