Support rejecting calls

Use the 'reject' method when we want to reject an incoming call
rather than end one that's in progress. Also get our error messages
right for the other side rejecting the call (albeit still with
placeholder dialog-box UX).

Requires https://github.com/matrix-org/matrix-js-sdk/pull/1510

src/components/views/rooms/EventTile.js

@@ -46,6 +46,7 @@ const eventTileTypes = {
     'm.call.invite': 'messages.TextualEvent',
     'm.call.answer': 'messages.TextualEvent',
     'm.call.hangup': 'messages.TextualEvent',
+    'm.call.reject': 'messages.TextualEvent',
 };
 
 const stateEventTileTypes = {

src/components/views/rooms/MessageComposer.js

@@ -38,6 +38,7 @@ import WidgetUtils from "../../../utils/WidgetUtils";
 import {UPDATE_EVENT} from "../../../stores/AsyncStore";
 import ActiveWidgetStore from "../../../stores/ActiveWidgetStore";
 import { PlaceCallType } from "../../../CallHandler";
+import { CallState } from 'matrix-js-sdk/src/webrtc/call';
 
 function ComposerAvatar(props) {
     const MemberStatusMessageAvatar = sdk.getComponent('avatars.MemberStatusMessageAvatar');
@@ -104,8 +105,11 @@ function HangupButton(props) {
         if (!call) {
             return;
         }
+
+        const action = call.state === CallState.Ringing ? 'reject' : 'hangup';
+
         dis.dispatch({
-            action: 'hangup',
+            action,
             // hangup the call for this room, which may not be the room in props
             // (e.g. conferences which will hangup the 1:1 room instead)
             room_id: call.roomId,

src/components/views/voip/IncomingCallBox.tsx

@@ -78,7 +78,7 @@ export default class IncomingCallBox extends React.Component<IProps, IState> {
     private onRejectClick: React.MouseEventHandler = (e) => {
         e.stopPropagation();
         dis.dispatch({
-            action: 'hangup',
+            action: 'reject',
             room_id: this.state.incomingCall.roomId,
         });
     };