Adding third_party/openh264/src, build files and unittests

third_party/openh264/testing/i420_utils.h

+// 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.
+
+#ifndef OPENH264_TESTING_I420_UTILS_H_
+#define OPENH264_TESTING_I420_UTILS_H_
+
+#include "webrtc/video_frame.h"
+
+namespace openh264 {
+
+void RgbToYuv(uint8_t r, uint8_t g, uint8_t b,
+              uint8_t* y, uint8_t* u, uint8_t* v);
+
+void YuvToRgb(uint8_t y, uint8_t u, uint8_t v,
+              uint8_t* r, uint8_t* g, uint8_t* b);
+
+void CreateRgbFrame(webrtc::VideoFrame* video_frame, int width, int height,
+                    uint8_t r, uint8_t g, uint8_t b);
+
+}  // namespace openh264
+
+#endif  // OPENH264_TESTING_I420_UTILS_H_