Adding third_party/openh264/src, build files and unittests

third_party/openh264/tests/BUILD.gn

Index: third_party/openh264/tests/BUILD.gn
diff --git a/third_party/openh264/tests/BUILD.gn b/third_party/openh264/tests/BUILD.gn
deleted file mode 100644
index 5441a99a393fd97a4d7ba6a7c2378001bd20d4f0..0000000000000000000000000000000000000000
--- a/third_party/openh264/tests/BUILD.gn
+++ /dev/null
@@ -1,20 +0,0 @@
-# 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.
-
-import("//testing/test.gni")
-
-test("openh264_unittests") {
-  include_dirs = [
-    "//",
-    "//third_party",
-  ]
-
-  deps = [
-    "//testing/gtest",
-  ]
-
-  sources = [
-    "openh264_unittests.cc",
-  ]
-}