Adding third_party/openh264 build files for encoding

build/config/features.gni

Index: build/config/features.gni
diff --git a/build/config/features.gni b/build/config/features.gni
index d8ddb4743ab76fad43f55935eb525c5ecf8d4fc0..9bf297c6ffa22faea26d6dad20e64701d4686b41 100644
--- a/build/config/features.gni
+++ b/build/config/features.gni
@@ -54,6 +54,12 @@ declare_args() {
   # TODO(GYP) make mac work.
   enable_webrtc = !is_ios && !is_mac
 
+  # Enable this to build OpenH264.
+  # CHECK THE OPENH264 LICENSE BEFORE BUILDING. The default value should be 0,
+  # the open source version of Chromium should not build this by default due to
+  # license and patent reasons.
+  use_openh264 = true

[phoglund_chromium, 2015/11/16 14:51:41]

Same here.

[phoglund_chromium, 2015/11/16 14:52:21]

Acknowledged.

[Dirk Pranke, 2015/11/17 02:54:19]

"The default value should be false", not 0.

Also, would we want these to default to true in an official build? If so, we
should
make that be the case rather than require anyone who wants an official build
to have to specify additional flags.
 

[Dirk Pranke, 2015/11/17 23:49:14]

One more comment ... we shouldn't be adding new settings to features.gni unless
they tend to affect targets globally (which this one doesn't). Can you move this
to its own standalone *.gni file and then include it as needed?

[hbos_chromium, 2015/11/18 15:55:03]

Done.

Did the corresponding thing for gyp.
+ openh264_args.gni: defaults use_openh264 to is_chrome_branded.
+ openh264_args.gypi: defaults use_openh264 to 1 if branding=="Chrome", else 0.

In both cases you can override the default value (GYP_DEFINES or gn args),
regardless of if you're building chrome or chromium.

+
   # Enables the Media Router.
   enable_media_router = !is_ios