Sort event list if any event time was clamped

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 182465bd71f14cdad4b01231585a49e0326eef01..5a5448d901ce3a5300f79910aa774055975cf4c1 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioParamTimeline.cpp
@@ -471,6 +471,7 @@ float AudioParamTimeline::valuesForFrameRangeImpl(size_t startFrame,
   int numberOfEvents = m_events.size();
 
   if (numberOfEvents > 0) {
+    bool clampedSomeEventTime = false;
     double currentTime = startFrame / sampleRate;
 
     // Look at all the events in the timeline and check to see if any needs
@@ -482,8 +483,10 @@ float AudioParamTimeline::valuesForFrameRangeImpl(size_t startFrame,
       // in the past so clamp the event time to the current time (start of
       // the rendering quantum).
       if (event.needsTimeClampCheck()) {
-        if (event.time() < currentTime)
+        if (event.time() < currentTime) {
           event.setTime(currentTime);
+          clampedSomeEventTime = true;
+        }
 
         // In all cases, we can clear the flag because the event is either
         // in the future, or we've already checked it (just now).
@@ -491,6 +494,14 @@ float AudioParamTimeline::valuesForFrameRangeImpl(size_t startFrame,
       }
     }
 
+    if (clampedSomeEventTime) {
+      // If we clamped some event time to current time, we need to
+      // sort the event list in time order again, but it must be
+      // stable!
+      std::stable_sort(m_events.begin(), m_events.end(),
+                       ParamEvent::eventPreceeds);
+    }
+
     // Optimize the case where the last event is in the past.
     ParamEvent& lastEvent = m_events[m_events.size() - 1];
     ParamEvent::Type lastEventType = lastEvent.getType();
@@ -646,6 +657,7 @@ float AudioParamTimeline::valuesForFrameRangeImpl(size_t startFrame,
     float value2 = nextEvent ? nextEvent->value() : value1;
     double time2 = nextEvent ? nextEvent->time() : endFrame / sampleRate + 1;
 
+    DCHECK_GE(time2, time1);
     double deltaTime = time2 - time1;
     float k = deltaTime > 0 ? 1 / deltaTime : 0;