Revert of Pass task runners to AudioManager constructor.

components/audio_modem/audio_recorder_impl.h

Index: components/audio_modem/audio_recorder_impl.h
diff --git a/components/audio_modem/audio_recorder_impl.h b/components/audio_modem/audio_recorder_impl.h
index b0f5486c2c78b82a07a138d642d14618341f35ad..cce75fb2067ebf5eee9c9691bbc95555b687253e 100644
--- a/components/audio_modem/audio_recorder_impl.h
+++ b/components/audio_modem/audio_recorder_impl.h
@@ -79,6 +79,10 @@
               double volume) override;
   void OnError(media::AudioInputStream* stream) override;
 
+  // Flushes the audio loop, making sure that any queued operations are
+  // performed.
+  void FlushAudioLoopForTesting();
+
   bool is_recording_;
 
   media::AudioInputStream* stream_;