bug 1388656 re-initialize the Reverb only once when the ConvolverNode buffer changes r=padenot

MozReview-Commit-ID: IKMK5GYVRBB

--HG--
extra : transplant_source : DT%17%04%FF%A2%3A%C2%E7%E1%99j%0Cs%09%EA2%25%FE%03
extra : histedit_source : 7e88e9ef61f525c1c88aa5d29a70e8facf910f82

dom/media/webaudio/ConvolverNode.cpp

@@ -66,7 +66,8 @@ public:
     switch (aIndex) {
     case SAMPLE_RATE:
       mSampleRate = aParam;
-      AdjustReverb();
+      // The buffer is passed after the sample rate.
+      // mReverb will be set using this sample rate when the buffer is received.
       break;
     default:
       NS_ERROR("Bad ConvolverNodeEngine DoubleParameter");
@@ -75,11 +76,7 @@ public:
   void SetBuffer(already_AddRefed<ThreadSharedFloatArrayBufferList> aBuffer) override
   {
     mBuffer = aBuffer;
-    AdjustReverb();
-  }
 
-  void AdjustReverb()
-  {
     // Note about empirical tuning (this is copied from Blink)
     // The maximum FFT size affects reverb performance and accuracy.
     // If the reverb is single-threaded and processes entirely in the real-time audio thread,