Adding third_party/openh264 build files for encoding

third_party/openh264/openh264_args.gypi

+# 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.
+
+{
+  'variables': {
+    'conditions': [
+      # Enable this to build OpenH264.
+      # CHECK THE OPENH264 LICENSE BEFORE BUILDING. Chrome builds this by
+      # default, but non-Chrome builds need this to default to 0 due to license
+      # and patent reasons, see http://www.openh264.org/. In both cases the
+      # default value can be overwritten.
+      ['branding == "Chrome"', {
+        'use_openh264%': 1,
+      }, {
+        'use_openh264%': 0,
+      }],
+    ],
+  },
+}