[ui] Remove trackRegistry & move SliceRect to public.
This patch tidies up track.ts a little.
`TrackRegistry` wasn't being used anymore and SliceRect is used in the
`Track` interface which is defined in public and which plugins make use
of, so it makes sense to move it into public as well.
Change-Id: I6a19d60e4867822a99e1731a624cc93af2bc18f8
diff --git a/ui/src/common/basic_async_track.ts b/ui/src/common/basic_async_track.ts
index 41dfe3d..d5e0dda 100644
--- a/ui/src/common/basic_async_track.ts
+++ b/ui/src/common/basic_async_track.ts
@@ -18,8 +18,7 @@
import {raf} from '../core/raf_scheduler';
import {globals} from '../frontend/globals';
import {PxSpan, TimeScale} from '../frontend/time_scale';
-import {SliceRect} from '../frontend/track';
-import {Track, TrackContext} from '../public';
+import {SliceRect, Track, TrackContext} from '../public';
import {TrackData} from './track_data';