Reland of Prepare for injectable SW decoders

webrtc/api/video_codecs/sdp_video_format.h

+/*
+ *  Copyright (c) 2017 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_API_VIDEO_CODECS_SDP_VIDEO_FORMAT_H_
+#define WEBRTC_API_VIDEO_CODECS_SDP_VIDEO_FORMAT_H_
+
+#include <map>
+#include <string>
+
+namespace webrtc {
+
+// SDP specification for a single video codec.
+// NOTE: This class is still under development and may change without notice.
+struct SdpVideoFormat {
+  using Parameters = std::map<std::string, std::string>;
+
+  explicit SdpVideoFormat(const std::string& name) : name(name) {}
+  SdpVideoFormat(const std::string& name, const Parameters& parameters)
+      : name(name), parameters(parameters) {}
+
+  friend bool operator==(const SdpVideoFormat& a, const SdpVideoFormat& b) {
+    return a.name == b.name && a.parameters == b.parameters;
+  }
+
+  friend bool operator!=(const SdpVideoFormat& a, const SdpVideoFormat& b) {
+    return !(a == b);
+  }
+
+  std::string name;
+  Parameters parameters;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_API_VIDEO_CODECS_SDP_VIDEO_FORMAT_H_