[Chromecast] Disable secure FLAC and OPUS codec in EME on Chromecast V1.

BUG=internal b/115688282

Test=cast to Chromecast V1 from Google Play Movie.

Change-Id: Ic57c4861016066457d850ace0f9da8e3cd905959
Reviewed-on: https://chromium-review.googlesource.com/1237613
Commit-Queue: Ziyang Cheng <ziyangch@chromium.org>
Reviewed-by: Yuchen Liu <yucliu@chromium.org>
Reviewed-by: Sergey Volk <servolk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593748}

chromecast/BUILD.gn

@@ -592,6 +592,7 @@ buildflag_header("chromecast_buildflags") {
     "USE_ANDROID_USER_AGENT=$use_android_user_agent",
     "USE_CHROMECAST_CDMS=$use_chromecast_cdms",
     "DEFAULT_COMMAND_LINE_FLAGS=\"$default_command_line_flags\"",
+    "DISABLE_SECURE_FLAC_OPUS_DECODING=$disable_secure_flac_and_opus_decoding",
   ]
 }
 

chromecast/chromecast.gni

@@ -94,6 +94,10 @@ declare_args() {
   # This arg can be overridden but not supports += operator.
   # TODO(ziyangch): make the parsing logic have ability to quote/escape characters.
   default_command_line_flags = ""
+
+  # Set to true to disable secure flac/opus support in EME, when using
+  # cast CMA media backend and supporting Widevine or Playready.
+  disable_secure_flac_and_opus_decoding = false
 }
 
 declare_args() {

chromecast/renderer/media/key_systems_cast.cc

@@ -112,10 +112,13 @@ class PlayReadyKeySystemProperties : public ::media::KeySystemProperties {
 SupportedCodecs GetCastEmeSupportedCodecs() {
   SupportedCodecs codecs =
       ::media::EME_CODEC_MP4_AAC | ::media::EME_CODEC_MP4_AVC1 |
-      ::media::EME_CODEC_MP4_FLAC | ::media::EME_CODEC_COMMON_VP9 |
-      ::media::EME_CODEC_WEBM_OPUS | ::media::EME_CODEC_WEBM_VP8 |
+      ::media::EME_CODEC_COMMON_VP9 | ::media::EME_CODEC_WEBM_VP8 |
       ::media::EME_CODEC_WEBM_VP9;
 
+#if !BUILDFLAG(DISABLE_SECURE_FLAC_OPUS_DECODING)
+  codecs |= ::media::EME_CODEC_MP4_FLAC | ::media::EME_CODEC_WEBM_OPUS;
+#endif  // BUILDFLAG(DISABLE_SECURE_FLAC_OPUS_DECODING)
+
 #if BUILDFLAG(ENABLE_HEVC_DEMUXING)
   codecs |= ::media::EME_CODEC_MP4_HEVC;
 #endif  // BUILDFLAG(ENABLE_HEVC_DEMUXING)