Add config option to turn on in-room event sending timing metrics

This is intended to be hooked up to an external system. 

Due to the extra events and metadata concerns, this is only available if turned on from the config.

See `sendTimePerformanceMetrics.ts` for event schemas.

src/ContentMessages.tsx

@@ -39,6 +39,8 @@ import {
 import { IUpload } from "./models/IUpload";
 import { IAbortablePromise, IImageInfo } from "matrix-js-sdk/src/@types/partials";
 import { BlurhashEncoder } from "./BlurhashEncoder";
+import SettingsStore from "./settings/SettingsStore";
+import { decorateStartSendingTime, sendRoundTripMetric } from "./sendTimePerformanceMetrics";
 
 const MAX_WIDTH = 800;
 const MAX_HEIGHT = 600;
@@ -539,6 +541,10 @@ export default class ContentMessages {
             msgtype: "", // set later
         };
 
+        if (SettingsStore.getValue("Performance.addSendMessageTimingMetadata")) {
+            decorateStartSendingTime(content);
+        }
+
         // if we have a mime type for the file, add it to the message metadata
         if (file.type) {
             content.info.mimetype = file.type;
@@ -614,6 +620,11 @@ export default class ContentMessages {
         }).then(function() {
             if (upload.canceled) throw new UploadCanceledError();
             const prom = matrixClient.sendMessage(roomId, content);
+            if (SettingsStore.getValue("Performance.addSendMessageTimingMetadata")) {
+                prom.then(resp => {
+                    sendRoundTripMetric(matrixClient, roomId, resp.event_id);
+                });
+            }
             CountlyAnalytics.instance.trackSendMessage(startTime, prom, roomId, false, false, content);
             return prom;
         }, function(err) {