Support audio output device enumeration and selection in PPAPI

ppapi/c/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # These are just headers.
 source_set("c") {
   sources = [
     "pp_array_output.h",
     "pp_bool.h",
     "pp_codecs.h",
@@ skipping 69 matching lines @@
     "ppp_message_handler.h",
     "ppp_messaging.h",
     "ppp_mouse_lock.h",
 
     # Dev interfaces.
     "dev/pp_cursor_type_dev.h",
     "dev/pp_print_settings_dev.h",
     "dev/pp_video_capture_dev.h",
     "dev/pp_video_dev.h",
     "dev/ppb_audio_input_dev.h",
+    "dev/ppb_audio_output_dev.h",
     "dev/ppb_buffer_dev.h",
     "dev/ppb_char_set_dev.h",
     "dev/ppb_crypto_dev.h",
     "dev/ppb_cursor_control_dev.h",
     "dev/ppb_device_ref_dev.h",
     "dev/ppb_file_chooser_dev.h",
     "dev/ppb_gles_chromium_texture_mapping_dev.h",
     "dev/ppb_ime_input_event_dev.h",
     "dev/ppb_memory_dev.h",
     "dev/ppb_opengles2ext_dev.h",
@@ skipping 65 matching lines @@
 
     # Trusted interfaces.
     "trusted/ppb_broker_trusted.h",
     "trusted/ppb_browser_font_trusted.h",
     "trusted/ppb_char_set_trusted.h",
     "trusted/ppb_file_chooser_trusted.h",
     "trusted/ppb_url_loader_trusted.h",
     "trusted/ppp_broker.h",
   ]
 }