Factor out AudioOutputDelegate from AudioRendererHost.

content/browser/BUILD.gn

Index: content/browser/BUILD.gn
diff --git a/content/browser/BUILD.gn b/content/browser/BUILD.gn
index 5bd8c9819d0fd4fb47d5ffa7d19fc118166abc3b..94e8681b1da861727ce8b07eca0bbd5250ec6721 100644
--- a/content/browser/BUILD.gn
+++ b/content/browser/BUILD.gn
@@ -291,6 +291,8 @@ source_set("browser") {
     "appcache/appcache_working_set.h",
     "appcache/chrome_appcache_service.cc",
     "appcache/chrome_appcache_service.h",
+    "audio_device_thread.cc",
+    "audio_device_thread.h",
     "background_sync/background_sync_context.cc",
     "background_sync/background_sync_context.h",
     "background_sync/background_sync_manager.cc",
@@ -1087,6 +1089,8 @@ source_set("browser") {
     "renderer_host/media/audio_input_sync_writer.h",
     "renderer_host/media/audio_output_authorization_handler.cc",
     "renderer_host/media/audio_output_authorization_handler.h",
+    "renderer_host/media/audio_output_delegate.cc",
+    "renderer_host/media/audio_output_delegate.h",
     "renderer_host/media/audio_renderer_host.cc",
     "renderer_host/media/audio_renderer_host.h",
     "renderer_host/media/audio_sync_reader.cc",