location sharing: fix thread issue

Fixes an issue regarding the location sharing
noticed on the Beta channel.

Change-Id: I3832aa50a816c0c1345e2a8f21853319f8791629

ring-android/app/src/main/java/cx/ring/fragments/LocationSharingFragment.java

@@ -294,7 +294,9 @@ public class LocationSharingFragment extends Fragment {
         mDisposableBag.add(mServiceDisposableBag);
         mDisposableBag.add(mShowControlsSubject.subscribe(this::setShowControls));
         mDisposableBag.add(mIsSharingSubject.subscribe(this::setIsSharing));
-        mDisposableBag.add(mShowMapSubject.subscribe(state -> {
+        mDisposableBag.add(mShowMapSubject
+                .subscribeOn(AndroidSchedulers.mainThread())
+                .subscribe(state -> {
                     Fragment p = getParentFragment();
                     if (p instanceof ConversationFragment) {
                         ConversationFragment parent = (ConversationFragment) p;