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

webrtc/media/base/videobroadcaster.cc

Index: webrtc/media/base/videobroadcaster.cc
diff --git a/webrtc/media/base/videobroadcaster.cc b/webrtc/media/base/videobroadcaster.cc
index 6655d9365631a690627b7d3fd9dbc55a7e9a3ec5..85494a4e9e810b002b55cbfc803963e417cb838a 100644
--- a/webrtc/media/base/videobroadcaster.cc
+++ b/webrtc/media/base/videobroadcaster.cc
@@ -89,18 +89,18 @@ void VideoBroadcaster::UpdateWants() {
          (*sink.wants.max_pixel_count < *wants.max_pixel_count))) {
       wants.max_pixel_count = sink.wants.max_pixel_count;
     }
-    // wants.max_pixel_count_step_up == MIN(sink.wants.max_pixel_count_step_up)
-    if (sink.wants.max_pixel_count_step_up &&
-        (!wants.max_pixel_count_step_up ||
-         (*sink.wants.max_pixel_count_step_up <
-          *wants.max_pixel_count_step_up))) {
-      wants.max_pixel_count_step_up = sink.wants.max_pixel_count_step_up;
+    // Select the minimum requested target_pixel_count, if any, of all sinks so

[nisse-webrtc, 2017/02/06 08:43:19]

Sinks could use max_pixel_count to express a limit. So one could use average or
median instead of minimum, right?

Probably best to stick to minimum for now, though, if that's closest to the old
behavior.

Ultimately, we'd like to support separate dimensions for each sink, possibly
pushing actual scaling further down the pipeline.

[sprang_webrtc, 2017/02/06 10:34:02]

I wasn't aware of the full context of this behavior so tried to stick close to
the previous behavior.
Agree that it could make sense to do something "smarter" if we can express the
limit with max, but let's not do that in another cl in that case. I'll add a
todo.

+    // that we don't over utilize the resources for any one.
+    if (sink.wants.target_pixel_count &&
+        (!wants.target_pixel_count ||
+         (*sink.wants.target_pixel_count < *wants.target_pixel_count))) {
+      wants.target_pixel_count = sink.wants.target_pixel_count;
     }
   }
 
-  if (wants.max_pixel_count && wants.max_pixel_count_step_up &&
-      *wants.max_pixel_count_step_up >= *wants.max_pixel_count) {
-    wants.max_pixel_count_step_up = Optional<int>();
+  if (wants.max_pixel_count && wants.target_pixel_count &&
+      *wants.target_pixel_count >= *wants.max_pixel_count) {
+    wants.target_pixel_count = wants.max_pixel_count;
   }
   current_wants_ = wants;
 }