perfetto-ui: Implement pinning for tracks

Change-Id: Iddd074a895d35005bf453b4eb60e88cf7770081f
diff --git a/ui/src/common/state.ts b/ui/src/common/state.ts
index a57d979..c1fe8b4 100644
--- a/ui/src/common/state.ts
+++ b/ui/src/common/state.ts
@@ -79,7 +79,8 @@
   traceTime: TraceTime;
   visibleTraceTime: TraceTime;
   tracks: ObjectById<TrackState>;
-  displayedTrackIds: string[];
+  scrollingTracks: string[];
+  pinnedTracks: string[];
   queries: ObjectById<QueryConfig>;
   permalink: PermalinkConfig;
   status: Status;
@@ -93,7 +94,8 @@
     traceTime: {startSec: 0, endSec: 10, lastUpdate: 0},
     visibleTraceTime: {startSec: 0, endSec: 10, lastUpdate: 0},
     tracks: {},
-    displayedTrackIds: [],
+    pinnedTracks: [],
+    scrollingTracks: [],
     queries: {},
     permalink: {},
     status: {msg: '', timestamp: 0},