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diff --git a/third_party/libwebrtc/call/adaptation/video_source_restrictions.h b/third_party/libwebrtc/call/adaptation/video_source_restrictions.h
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+/*
+ *  Copyright 2020 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 CALL_ADAPTATION_VIDEO_SOURCE_RESTRICTIONS_H_
+#define CALL_ADAPTATION_VIDEO_SOURCE_RESTRICTIONS_H_
+
+#include <string>
+#include <utility>
+
+#include "absl/types/optional.h"
+
+namespace webrtc {
+
+// Describes optional restrictions to the resolution and frame rate of a video
+// source.
+class VideoSourceRestrictions {
+ public:
+  // Constructs without any restrictions.
+  VideoSourceRestrictions();
+  // All values must be positive or nullopt.
+  // TODO(hbos): Support expressing "disable this stream"?
+  VideoSourceRestrictions(absl::optional<size_t> max_pixels_per_frame,
+                          absl::optional<size_t> target_pixels_per_frame,
+                          absl::optional<double> max_frame_rate);
+
+  bool operator==(const VideoSourceRestrictions& rhs) const {
+    return max_pixels_per_frame_ == rhs.max_pixels_per_frame_ &&
+           target_pixels_per_frame_ == rhs.target_pixels_per_frame_ &&
+           max_frame_rate_ == rhs.max_frame_rate_;
+  }
+  bool operator!=(const VideoSourceRestrictions& rhs) const {
+    return !(*this == rhs);
+  }
+
+  std::string ToString() const;
+
+  // The source must produce a resolution less than or equal to
+  // max_pixels_per_frame().
+  const absl::optional<size_t>& max_pixels_per_frame() const;
+  // The source should produce a resolution as close to the
+  // target_pixels_per_frame() as possible, provided this does not exceed
+  // max_pixels_per_frame().
+  // The actual pixel count selected depends on the capabilities of the source.
+  // TODO(hbos): Clarify how "target" is used. One possible implementation: open
+  // the camera in the smallest resolution that is greater than or equal to the
+  // target and scale it down to the target if it is greater. Is this an
+  // accurate description of what this does today, or do we do something else?
+  const absl::optional<size_t>& target_pixels_per_frame() const;
+  const absl::optional<double>& max_frame_rate() const;
+
+  void set_max_pixels_per_frame(absl::optional<size_t> max_pixels_per_frame);
+  void set_target_pixels_per_frame(
+      absl::optional<size_t> target_pixels_per_frame);
+  void set_max_frame_rate(absl::optional<double> max_frame_rate);
+
+  // Update `this` with min(`this`, `other`).
+  void UpdateMin(const VideoSourceRestrictions& other);
+
+ private:
+  // These map to rtc::VideoSinkWants's `max_pixel_count` and
+  // `target_pixel_count`.
+  absl::optional<size_t> max_pixels_per_frame_;
+  absl::optional<size_t> target_pixels_per_frame_;
+  absl::optional<double> max_frame_rate_;
+};
+
+bool DidRestrictionsIncrease(VideoSourceRestrictions before,
+                             VideoSourceRestrictions after);
+bool DidRestrictionsDecrease(VideoSourceRestrictions before,
+                             VideoSourceRestrictions after);
+bool DidIncreaseResolution(VideoSourceRestrictions restrictions_before,
+                           VideoSourceRestrictions restrictions_after);
+bool DidDecreaseResolution(VideoSourceRestrictions restrictions_before,
+                           VideoSourceRestrictions restrictions_after);
+bool DidIncreaseFrameRate(VideoSourceRestrictions restrictions_before,
+                          VideoSourceRestrictions restrictions_after);
+bool DidDecreaseFrameRate(VideoSourceRestrictions restrictions_before,
+                          VideoSourceRestrictions restrictions_after);
+
+}  // namespace webrtc
+
+#endif  // CALL_ADAPTATION_VIDEO_SOURCE_RESTRICTIONS_H_