Propagate connected user to web app.

remoting/webapp/me2mom/_locales/en/messages.json

 {
   "accessCode": {
     "message": "Access code",
     "description": "Label for the access code entry box"
   },
   "accessCodeTimer": {
     "message": "This access code will expire in",
     "description": "Text preceding the access code timer"
   },
   "authenticateButton": {
@@ skipping 94 matching lines @@
   },
   "messageGenerating": {
     "message": "Generating access code…",
     "description": "Text shown while generating an access code"
   },
   "messageSessionFinished": {
     "message": "You are no longer connected to the remote desktop.",
     "description": "Message displayed when the client has (been) disconnected"
   },
   "messageShared": {
-    "message": "Your desktop is currently being shared.",
-    "description": "Message shown on the host computer while a session is active"
+    "message": "Your desktop is currently being shared with $USER$.",
+    "description": "Message shown on the host computer while a session is active",
+    "placeholders": {
+      "user": {
+        "content": "$1",
+        "example": "user@domain.com"
+      }
+    }
   },
   "modeShare": {
     "message": "Share",
     "description": "Sub-title for the host app"
   },
   "modeConnect": {
     "message": "Connect",
     "description": "Sub-title for the client app"
   },
   "oauth2TokenLabel": {
@@ skipping 34 matching lines @@
   },
   "webappDescription": {
     "message": "IT2Me-style remote support in Chrome.",
     "description": "Web-app description"
   },
   "webappName": {
     "message": "Remoting IT2Me",
     "description": "Web-app name"
   }
 }