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..1a6a995c1d2dbb8c6901026a82da40c034563c6b 100644
--- a/content/browser/renderer_host/media/audio_renderer_host.cc
+++ b/content/browser/renderer_host/media/audio_renderer_host.cc
@@ -495,7 +495,13 @@ 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.
+      content::bad_message::ReceivedBadMessage(
+          this, bad_message::ARH_CREATED_STREAM_WITHOUT_AUTHORIZATION);
+      return;
+    }
     device_unique_id.swap(auth_data->second.second);
     authorizations_.erase(auth_data);
   }