Reland: Pass task runners to AudioManager constructor.

media/mojo/services/mojo_media_client.cc

Index: media/mojo/services/mojo_media_client.cc
diff --git a/media/mojo/services/mojo_media_client.cc b/media/mojo/services/mojo_media_client.cc
index 2d81841b7db932c96c9c15360f12276478c5cf0a..56d16b09fbebb8370dd7eb1c9599618e3568a284 100644
--- a/media/mojo/services/mojo_media_client.cc
+++ b/media/mojo/services/mojo_media_client.cc
@@ -12,6 +12,8 @@ MojoMediaClient::~MojoMediaClient() {}
 
 void MojoMediaClient::Initialize() {}
 
+void MojoMediaClient::WillQuit() {}
+
 std::unique_ptr<AudioDecoder> MojoMediaClient::CreateAudioDecoder(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
   return nullptr;