Revert bug 1647717 to workaround the issue of occational tab crashing when
using any cubeb backends other than pulse-rust to play media. The loss of
such change will be that users will not be able to do profiling on threads
created by libcubeb.

--- dom/media/AudioStream.cpp.orig	2021-03-20 22:57:21.194862000 +0100
+++ dom/media/AudioStream.cpp	2021-03-20 23:00:50.527112000 +0100
@@ -26,7 +26,6 @@
 #endif
 #include "Tracing.h"
 #include "webaudio/blink/DenormalDisabler.h"
-#include "AudioThreadRegistry.h"
 
 // Use abort() instead of exception in SoundTouch.
 #define ST_NO_EXCEPTION_HANDLING 1
@@ -139,9 +138,7 @@
       mTimeStretcher(nullptr),
       mState(INITIALIZED),
       mDataSource(aSource),
-      mPrefillQuirk(false),
-      mAudioThreadId(0),
-      mSandboxed(CubebUtils::SandboxEnabled()) {}
+      mPrefillQuirk(false) {}
 
 AudioStream::~AudioStream() {
   LOG("deleted, state %d", mState);
@@ -565,21 +562,7 @@
       aWriter.Available());
 }
 
-bool AudioStream::CheckThreadIdChanged() {
-#ifdef MOZ_GECKO_PROFILER
-  auto id = profiler_current_thread_id();
-  if (id != mAudioThreadId) {
-    mAudioThreadId = id;
-    return true;
-  }
-#endif
-  return false;
-}
-
 long AudioStream::DataCallback(void* aBuffer, long aFrames) {
-  if (!mSandboxed && CheckThreadIdChanged()) {
-    CubebUtils::GetAudioThreadRegistry()->Register(mAudioThreadId);
-  }
   WebCore::DenormalDisabler disabler;
 
   TRACE_AUDIO_CALLBACK_BUDGET(aFrames, mAudioClock.GetInputRate());
@@ -635,9 +618,6 @@
   mDumpFile.Write(static_cast<const AudioDataValue*>(aBuffer),
                   aFrames * mOutChannels);
 
-  if (!mSandboxed && writer.Available() != 0) {
-    CubebUtils::GetAudioThreadRegistry()->Unregister(mAudioThreadId);
-  }
   return aFrames - writer.Available();
 }
 
--- dom/media/AudioStream.h.orig	2021-03-20 23:01:10.169773000 +0100
+++ dom/media/AudioStream.h	2021-03-20 23:01:56.622691000 +0100
@@ -294,7 +294,6 @@
 
   template <typename Function, typename... Args>
   int InvokeCubeb(Function aFunction, Args&&... aArgs);
-  bool CheckThreadIdChanged();
 
   // The monitor is held to protect all access to member variables.
   Monitor mMonitor;
@@ -328,9 +327,6 @@
   // the default device is used. It is set
   // during the Init() in decoder thread.
   RefPtr<AudioDeviceInfo> mSinkInfo;
-  /* Contains the id of the audio thread, from profiler_get_thread_id. */
-  std::atomic<int> mAudioThreadId;
-  const bool mSandboxed = false;
 
   MozPromiseHolder<MediaSink::EndedPromise> mEndedPromise;
   Atomic<bool> mPlaybackComplete;