Add support for writing raw encoder output to .ivf files.

webrtc/modules/video_coding/utility/ivf_file_writer.h

Index: webrtc/modules/video_coding/utility/ivf_file_writer.h
diff --git a/webrtc/modules/video_coding/utility/ivf_file_writer.h b/webrtc/modules/video_coding/utility/ivf_file_writer.h
new file mode 100644
index 0000000000000000000000000000000000000000..f2d658008c0b0375d2f9e5e2ed00a97c1d0ee93e
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+++ b/webrtc/modules/video_coding/utility/ivf_file_writer.h
@@ -0,0 +1,46 @@
+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_MODULES_VIDEO_CODING_UTILITY_IVF_FILE_WRITER_H_
+#define WEBRTC_MODULES_VIDEO_CODING_UTILITY_IVF_FILE_WRITER_H_
+
+#include <stdio.h>
+#include <memory>
+#include <string>
+
+#include "webrtc/common_types.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/video_frame.h"
+
+namespace webrtc {
+
+class IvfFileWriter {
+ public:
+  ~IvfFileWriter();
+
+  static std::unique_ptr<IvfFileWriter> Open(const char* file_name,
+                                             VideoCodecType codec_type);
+  bool WriteFrame(const EncodedImage& encoded_image);
+  bool Close();
+
+ private:
+  explicit IvfFileWriter(const char* file_name, FILE* file);
+  bool SeekTo(size_t offset);
+
+  size_t num_frames_;
+  const std::string file_name_;
+  FILE* file_;
+
+  RTC_DISALLOW_COPY_AND_ASSIGN(IvfFileWriter);
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_VIDEO_CODING_UTILITY_IVF_FILE_WRITER_H_