Bug 1277284 - Bustage fix in opt, on a CLOSED TREE.

MozReview-Commit-ID: LC7mBVas8CB

dom/media/GraphDriver.cpp

@@ -626,7 +626,7 @@ AudioCallbackDriver::Init()
                           mGraphImpl->mOutputWanted ? &output : nullptr, latency,
                           DataCallback_s, StateCallback_s, this) == CUBEB_OK) {
       mAudioStream.own(stream);
-      int rv = cubeb_stream_set_volume(mAudioStream, CubebUtils::GetVolumeScale());
+      DebugOnly<int> rv = cubeb_stream_set_volume(mAudioStream, CubebUtils::GetVolumeScale());
       NS_WARN_IF_FALSE(rv == CUBEB_OK,
           "Could not set the audio stream volume in GraphDriver.cpp");
     } else {