Change rtc::VideoSinkWants to have target and a max pixel count

webrtc/media/base/videosourceinterface.h

Index: webrtc/media/base/videosourceinterface.h
diff --git a/webrtc/media/base/videosourceinterface.h b/webrtc/media/base/videosourceinterface.h
index bae02c8d0fc3c453d199aa7853b08ecde299e136..0ea1c60abfa389e5bc236925e25d9bae74e2886d 100644
--- a/webrtc/media/base/videosourceinterface.h
+++ b/webrtc/media/base/videosourceinterface.h
@@ -28,12 +28,12 @@ struct VideoSinkWants {
 
   // Tells the source the maximum number of pixels the sink wants.
   rtc::Optional<int> max_pixel_count;
-  // Like |max_pixel_count| but relative to the given value. The source is
-  // requested to produce frames with a resolution one "step up" from the given
-  // value. In practice, this means that the sink can consume this amount of
-  // pixels but wants more and the source should produce a resolution one
-  // "step" higher than this but not higher.
-  rtc::Optional<int> max_pixel_count_step_up;
+  // Tells the source the desired number of pixels the sinks wants. This will
+  // typically be used when stepping the resolution up again when conditions
+  // have improved after an earlier downgrade. The source should select the
+  // closest resolution to this pixel count, but if max_pixel_count is set, it
+  // still sets the absolute upper bound.
+  rtc::Optional<int> target_pixel_count;
 };
 
 template <typename VideoFrameT>