Wire up the send button for voice messages

This fixes a bug where we couldn't upload voice messages because the audio buffer was being read, therefore changing the position of the cursor. When this happened, the upload function would claim that the buffer was empty and could not be read.

src/components/views/rooms/MessageComposer.tsx

@@ -198,6 +198,7 @@ interface IState {
 export default class MessageComposer extends React.Component<IProps, IState> {
     private dispatcherRef: string;
     private messageComposerInput: SendMessageComposer;
+    private voiceRecordingButton: VoiceRecordComposerTile;
 
     constructor(props) {
         super(props);
@@ -322,7 +323,15 @@ export default class MessageComposer extends React.Component<IProps, IState> {
         });
     }
 
-    sendMessage = () => {
+    sendMessage = async () => {
+        if (this.state.haveRecording && this.voiceRecordingButton) {
+            // There shouldn't be any text message to send when a voice recording is active, so
+            // just send out the voice recording.
+            await this.voiceRecordingButton.send();
+            return;
+        }
+
+        // XXX: Private function access
         this.messageComposerInput._sendMessage();
     }
 
@@ -387,6 +396,7 @@ export default class MessageComposer extends React.Component<IProps, IState> {
             if (SettingsStore.getValue("feature_voice_messages")) {
                 controls.push(<VoiceRecordComposerTile
                     key="controls_voice_record"
+                    ref={c => this.voiceRecordingButton = c}
                     room={this.props.room} />);
             }