Convert enable_mpeg2ts into a new-style buildflag

media/BUILD.gn

Index: media/BUILD.gn
diff --git a/media/BUILD.gn b/media/BUILD.gn
index 3180c7ac12320371f7cab2cf9d12f356816420fb..95d88860ab6123ed74920d9f8183dbdc72b18aa8 100644
--- a/media/BUILD.gn
+++ b/media/BUILD.gn
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/buildflag_header.gni")
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/features.gni")
@@ -10,6 +11,18 @@ import("//build/config/ui.gni")
 import("//media/media_options.gni")
 import("//testing/test.gni")
 
+buildflag_header("media_features") {
+  header = "media_features.h"
+
+  # Enables the MPEG2-TS stream parser for use with Media Source. Disabled by

[ddorwin, 2016/01/04 22:19:45]

This is consistent with the previous name but now more explicit. Are there no
plans to support .src=HEVC?

[servolk, 2016/01/05 00:18:09]

Did you mean .src=foo.ts (mpeg2ts)? AFAIK there's no short-term plans to support
that, since almost all Chromecast apps use MPL player that works through MSE.

[ddorwin, 2016/01/05 18:59:56]

Yes, oops. SG.

+  # default (except on Chromecast) since it's not available on the normal Web

[ddorwin, 2016/01/04 22:19:45]

Just keep it simple: Only supported on Chromecast.
Or just drop it since we can read the line below.

[servolk, 2016/01/05 00:18:09]

Done.

+  # Platform and costs money.
+  enable_mse_mpeg2ts_stream_parser = is_chromecast
+
+  flags =
+      [ "ENABLE_MSE_MPEG2TS_STREAM_PARSER=$enable_mse_mpeg2ts_stream_parser" ]
+}
+
 # Common configuration for targets in the media directory.
 # NOT for exporting.
 config("media_config") {
@@ -549,6 +562,7 @@ component("media") {
   }
 
   public_deps = [
+    ":media_features",
     "//media/audio",
     "//media/base",
     "//third_party/opus",