Add missing comments in selection-observer

src/annotator/bucket-bar-client.ts

@@ -10,7 +10,12 @@ import { computeAnchorPositions } from './util/buckets';
 type HostRPC = PortRPC<HostToGuestEvent, GuestToHostEvent>;
 
 export type BucketBarClientOptions = {
+  /**
+   * The scrollable container element for the document content. All the highlights
+   * that the bucket bar's buckets point at should be contained within this element.
+   */
   contentContainer: Element;
+
   hostRPC: HostRPC;
 };
 

src/annotator/selection-observer.ts

@@ -19,6 +19,7 @@ export function selectedRange(document: Document): Range | null {
  * An observer that watches for and buffers changes to the document's current selection.
  */
 export class SelectionObserver {
+  /** Tracks the timeout ID of the last scheduled callback */
   private _pendingCallback: number | null;
   private _document: Document;
   private _listeners: ListenerCollection;