Support HLS MPEG2 TS with SAMPLE-AES encryption.

media/media_options.gni

 # Copyright 2014 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.
 
 import("//build/config/chromecast_build.gni")
 import("//build/config/features.gni")
 import("//build/config/headless_build.gni")
 
 declare_args() {
   # Allows distributions to link pulseaudio directly (DT_NEEDED) instead of
@@ skipping 26 matching lines @@
   # it only provides demuxing, and is only useful for AC3/EAC3 audio
   # pass-through to HDMI sink on Chromecast.
   enable_ac3_eac3_audio_demuxing = proprietary_codecs && is_chromecast
 
   enable_mse_mpeg2ts_stream_parser = proprietary_codecs && is_chromecast
 
   # Enable HEVC/H265 demuxing. Actual decoding must be provided by the
   # platform. Enable by default for Chromecast.
   enable_hevc_demuxing = proprietary_codecs && is_chromecast
 
+  # Enable HLS with SAMPLE-AES decryption. Actual decryption must be provided by

[ddorwin, 2016/04/12 00:40:48]

Is the second sentence relevant? It's always provided by some CDM
implementation, right?

[dougsteed, 2016/05/08 23:18:45]

Done.

+  # the platform. Enabled by default on the cast desktop implementation to allow

[ddorwin, 2016/04/12 00:40:48]

nit: I suggest separating the explanation of the logic on a new line.

[dougsteed, 2016/05/08 23:18:45]

Done.

+  # unit tests of the MP2TS parsing support.
+  enable_hls_sample_aes = proprietary_codecs && is_cast_desktop_build
+
   # TODO(GYP): This should be a platform define.
   is_openbsd = false
 }
 
+# enable_hls_sample_aes can only be true if enable_mse_mpeg2ts_stream_parser is.
+assert(enable_mse_mpeg2ts_stream_parser || !enable_hls_sample_aes)
+
 # Use a second declare_args() to pick up possible overrides of |use_cras|.
 declare_args() {
   # Enables runtime selection of PulseAudio library.
   use_pulseaudio = false
 
   # Enables runtime selection of ALSA library for audio.
   use_alsa = false
 
   # Alsa should be used on non-Android, non-Mac POSIX systems.
   if (is_posix && !is_headless && !is_android && !is_mac) {
@@ skipping 55 matching lines @@
         "cdm",
         "renderer",
       ]
       mojo_media_host = "browser"
     } else {
       mojo_media_services = [ "cdm" ]
       mojo_media_host = "utility"
     }
   }
 }