Move direct use of VideoCapturer::VideoAdapter to VideoSinkWants.

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 14624585432194c74bec680c6f18befb56ce79f5..7b3853116f93f7ebeab065d148ef38e0b3892701 100644
--- a/webrtc/media/base/videosourceinterface.h
+++ b/webrtc/media/base/videosourceinterface.h
@@ -11,8 +11,11 @@
 #ifndef WEBRTC_MEDIA_BASE_VIDEOSOURCEINTERFACE_H_
 #define WEBRTC_MEDIA_BASE_VIDEOSOURCEINTERFACE_H_
 
+#include <limits>
+
 #include "webrtc/media/base/videosinkinterface.h"
 #include "webrtc/base/callback.h"
+#include "webrtc/base/optional.h"
 
 namespace rtc {
 
@@ -27,6 +30,9 @@ struct VideoSinkWants {
   // Tells the source whether the sink wants frames with rotation applied.
   // By default, the rotation is applied by the source.
   bool rotation_applied = true;
+
+  // Tells the source the maximum number of pixels the sink wants.
+  rtc::Optional<int> max_number_of_pixels;
 };
 
 template <typename VideoFrameT>