Add qualityLimitationResolutionChanges stat

Implements the stat qualityLimitationResolutionChanges [1].

[1] https://w3c.github.io/webrtc-stats/#dom-rtcoutboundrtpstreamstats-qualitylimitationresolutionchanges

Bug: webrtc:10935
Change-Id: I391f2be5958a96b442e32c40ab7043752f3f71dd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/150882
Reviewed-by: Erik Språng <sprang@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Evan Shrubsole <eshr@google.com>
Cr-Commit-Position: refs/heads/master@{#29113}
diff --git a/pc/rtc_stats_integrationtest.cc b/pc/rtc_stats_integrationtest.cc
index c36566a..29f0651 100644
--- a/pc/rtc_stats_integrationtest.cc
+++ b/pc/rtc_stats_integrationtest.cc
@@ -869,6 +869,8 @@
       verifier.TestMemberIsNonNegative<double>(
           outbound_stream.total_packet_send_delay);
       verifier.TestMemberIsDefined(outbound_stream.quality_limitation_reason);
+      verifier.TestMemberIsNonNegative<uint32_t>(
+          outbound_stream.quality_limitation_resolution_changes);
       // The integration test is not set up to test screen share; don't require
       // this to be present.
       verifier.MarkMemberTested(outbound_stream.content_type, true);
@@ -882,6 +884,8 @@
       // TODO(https://crbug.com/webrtc/10635): Implement for audio as well.
       verifier.TestMemberIsUndefined(outbound_stream.total_packet_send_delay);
       verifier.TestMemberIsUndefined(outbound_stream.quality_limitation_reason);
+      verifier.TestMemberIsUndefined(
+          outbound_stream.quality_limitation_resolution_changes);
       verifier.TestMemberIsUndefined(outbound_stream.content_type);
       // TODO(hbos): Implement for audio as well.
       verifier.TestMemberIsUndefined(outbound_stream.encoder_implementation);