Adds usage counters to RTCQuicTransport.

Adds usage counters for the datagram APIs on the RTCQuicTransport for
the origin trial.

Bug: 874296
Change-Id: Ifb3490b8bf0d3221f29c65a2d91830dbb8aeabd9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1573808
Commit-Queue: Seth Hampson <shampson@chromium.org>
Commit-Queue: Daniel Cheng <dcheng@chromium.org>
Auto-Submit: Seth Hampson <shampson@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Reviewed-by: Steve Anton <steveanton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652427}

third_party/blink/public/mojom/web_feature/web_feature.mojom

@@ -2271,6 +2271,10 @@ enum WebFeature {
   kHidDeviceSendReport = 2864,
   kHidGetDevices = 2865,
   kHidRequestDevice = 2866,
+  kV8RTCQuicTransport_MaxDatagramLength_AttributeGetter = 2867,
+  kV8RTCQuicTransport_ReadyToSendDatagram_Method = 2868,
+  kV8RTCQuicTransport_SendDatagram_Method = 2869,
+  kV8RTCQuicTransport_ReceiveDatagrams_Method = 2870,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.

third_party/blink/renderer/modules/peerconnection/rtc_quic_transport.idl

@@ -23,16 +23,16 @@ enum RTCQuicTransportState {
 ] interface RTCQuicTransport : EventTarget {
     [Measure] readonly attribute RTCIceTransport transport;
     [Measure] readonly attribute RTCQuicTransportState state;
-    readonly attribute unsigned short? maxDatagramLength;
+    [Measure] readonly attribute unsigned short? maxDatagramLength;
     [Measure] ArrayBuffer getKey();
     [Measure, RaisesException] void connect();
     [Measure, RaisesException] void listen(BufferSource remote_key);
     [Measure] void stop();
     [Measure, RaisesException] RTCQuicStream createStream();
-    [CallWith=ScriptState, RaisesException]
+    [CallWith=ScriptState, Measure, RaisesException]
     Promise<void> readyToSendDatagram();
-    [RaisesException] void sendDatagram(BufferSource data);
-    [CallWith=ScriptState, RaisesException]
+    [Measure, RaisesException] void sendDatagram(BufferSource data);
+    [CallWith=ScriptState, Measure, RaisesException]
     Promise<sequence<ArrayBuffer>> receiveDatagrams();
     [CallWith=ScriptState, Measure, RaisesException]
     Promise<RTCQuicTransportStats> getStats();

tools/metrics/histograms/enums.xml

@@ -22873,6 +22873,11 @@ Called by update_net_error_codes.py.-->
   <int value="2864" label="HidDeviceSendReport"/>
   <int value="2865" label="HidGetDevices"/>
   <int value="2866" label="HidRequestDevice"/>
+  <int value="2867"
+      label="V8RTCQuicTransport_MaxDatagramLength_AttributeGetter"/>
+  <int value="2868" label="V8RTCQuicTransport_ReadyToSendDatagram_Method"/>
+  <int value="2869" label="V8RTCQuicTransport_SendDatagram_Method"/>
+  <int value="2870" label="V8RTCQuicTransport_ReceiveDatagrams_Method"/>
 </enum>
 
 <enum name="FeaturePolicyFeature">