Bug 1846191 remove stream from mLiveStreams on audio thread when drai…

…ned or on error r=pehrsons

This removes one potentially dangling MockCubeb pointer, from the background
task, but this is mostly about the simplicity of removing while the lock is
still held.

Depends on D185024

Differential Revision: https://phabricator.services.mozilla.com/D185025

dom/media/gtest/MockCubeb.cpp

@@ -9,6 +9,8 @@
 
 namespace mozilla {
 
+using KeepProcessing = MockCubebStream::KeepProcessing;
+
 void PrintDevice(cubeb_device_info aInfo) {
   printf(
       "id: %zu\n"
@@ -339,11 +341,7 @@ MediaEventSource<void>& MockCubebStream::DeviceChangeForcedEvent() {
   return mDeviceChangedForcedEvent;
 }
 
-void MockCubebStream::Process10Ms() {
-  if (mStreamStop) {
-    return;
-  }
-
+KeepProcessing MockCubebStream::Process10Ms() {
   uint32_t rate = mHasOutput ? mOutputParams.rate : mInputParams.rate;
   const long nrFrames =
       static_cast<long>(static_cast<float>(rate * 10) * mDriftFactor) /
@@ -373,22 +371,13 @@ void MockCubebStream::Process10Ms() {
 
   if (outframes < nrFrames) {
     NotifyState(CUBEB_STATE_DRAINED);
-    mStreamStop = true;
-    return;
+    return KeepProcessing::No;
   }
   if (mForceErrorState) {
     mForceErrorState = false;
-    // Let the audio thread (this thread!) run to completion before
-    // being released, by joining and deleting on another thread.
-    NS_DispatchBackgroundTask(NS_NewRunnableFunction(
-        __func__, [cubeb = MockCubeb::AsMock(context), this,
-                   self = RefPtr<SmartMockCubebStream>(mSelf)] {
-          cubeb->StopStream(this);
-        }));
     NotifyState(CUBEB_STATE_ERROR);
     mErrorForcedEvent.Notify();
-    mStreamStop = true;
-    return;
+    return KeepProcessing::No;
   }
   if (mForceDeviceChanged) {
     mForceDeviceChanged = false;
@@ -402,6 +391,7 @@ void MockCubebStream::Process10Ms() {
           mDeviceChangedForcedEvent.Notify();
         }));
   }
+  return KeepProcessing::Yes;
 }
 
 void MockCubebStream::NotifyState(cubeb_state aState) {
@@ -654,8 +644,12 @@ void MockCubeb::ThreadFunction() {
     {
       auto streams = mLiveStreams.Lock();
       for (auto& stream : *streams) {
-        stream->Process10Ms();
+        auto keepProcessing = stream->Process10Ms();
+        if (keepProcessing == KeepProcessing::No) {
+          stream = nullptr;
+        }
       }
+      streams->RemoveElementsBy([](const auto& stream) { return !stream; });
       MOZ_ASSERT(mFakeAudioThread);
       if (streams->IsEmpty() && !mForcedAudioThread) {
         NS_DispatchBackgroundTask(NS_NewRunnableFunction(

dom/media/gtest/MockCubeb.h

@@ -201,7 +201,8 @@ class MockCubebStream {
   MediaEventSource<void>& ErrorForcedEvent();
   MediaEventSource<void>& DeviceChangeForcedEvent();
 
-  void Process10Ms();
+  enum class KeepProcessing { No, Yes };
+  KeepProcessing Process10Ms();
 
  public:
   const bool mHasInput;
@@ -216,7 +217,8 @@ class MockCubebStream {
   // Whether this stream should wait for an explicit start request before
   // starting. Protected by FrozenStartMonitor.
   bool mFrozenStart;
-  // Signal to the audio thread that stream is stopped.
+  // Used to abort a frozen start if cubeb_stream_start() is called currently
+  // with a blocked cubeb_stream_start() call.
   std::atomic_bool mStreamStop{true};
   // Whether or not the output-side of this stream (what is written from the
   // callback output buffer) is recorded in an internal buffer. The data is then