Remove dangerous CHECK. Add unit test.

content/browser/renderer_host/media/audio_renderer_host.cc

Index: content/browser/renderer_host/media/audio_renderer_host.cc
diff --git a/content/browser/renderer_host/media/audio_renderer_host.cc b/content/browser/renderer_host/media/audio_renderer_host.cc
index 77d21c86e51dc525f88568942af8f70d8a094911..affb2ffab837d83caaa336fad85d843a54a8d65f 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -495,7 +495,12 @@ void AudioRendererHost::OnCreateStream(int stream_id,
   std::string device_unique_id;
   const auto& auth_data = authorizations_.find(stream_id);
   if (auth_data != authorizations_.end()) {
-    CHECK(auth_data->second.first);
+    if (!auth_data->second.first) {
+      // The authorization for this stream is still pending, so it's an error
+      // to create it now.
+      SendErrorMessage(stream_id);

[Guido Urdaneta, 2016/10/04 09:57:11]

Since this should happen only with a bad renderer, wouldn't it be better to use
bad_message::ReceivedBadMessage?

+      return;
+    }
     device_unique_id.swap(auth_data->second.second);
     authorizations_.erase(auth_data);
   }