message: docs: add api doc for viewport scroller
  PR Close
diff: @@ -11,7 +11,7 @@ import {defineInjectable, inject} from '@angular/core';
  import {DOCUMENT} from './dom_tokens';
  /**
  - * Manages the scroll position.
  + * Defines a scroll position manager. Implemented by `BrowserViewportScroller`.
  *
  * @publicApi
  */
  @@ -24,40 +24,40 @@ export abstract class ViewportScroller {
  /**
  * Configures the top offset used when scrolling to an anchor.
  + * @param offset A position in screen coordinates (a tuple with x and y values)
  + * or a function that returns the top offset position.
  *
  - * When given a tuple with two number, the service will always use the numbers.
  - * When given a function, the service will invoke the function every time it restores scroll
  - * position.
  */
  abstract setOffset(offset: [number, number]|(() => [number, number])): void;
  /**
  - * Returns the current scroll position.
  + * Retrieves the current scroll position.
  + * @returns A position in screen coordinates (a tuple with x and y values).
  */
  abstract getScrollPosition(): [number, number];
  /**
  - * Sets the scroll position.
  + * Scrolls to a specified position.
  + * @param position A position in screen coordinates (a tuple with x and y values).
  */
  abstract scrollToPosition(position: [number, number]): void;
  /**
  - * Scrolls to the provided anchor.
  + * Scrolls to an anchor element.
  + * @param anchor The ID of the anchor element.
  */
  abstract scrollToAnchor(anchor: string): void;
  /**
  - *
  * Disables automatic scroll restoration provided by the browser.
  - *
  * See also [window.history.scrollRestoration
  - * info](https://developers.google.com/web/updates/2015/09/history-api-scroll-restoration)
  + * info](https://developers.google.com/web/updates/2015/09/history-api-scroll-restoration).
  */
  abstract setHistoryScrollRestoration(scrollRestoration: 'auto'|'manual'): void;
  }
  /**
  - * Manages the scroll position.
  + * Manages the scroll position for a browser window.
  */
  export class BrowserViewportScroller implements ViewportScroller {
  private offset: () => [number, number] = () => [0, 0];
  @@ -66,10 +66,9 @@ export class BrowserViewportScroller implements ViewportScroller {
  /**
  * Configures the top offset used when scrolling to an anchor.
  + * @param offset A position in screen coordinates (a tuple with x and y values)
  + * or a function that returns the top offset position.
  *
  - * * When given a number, the service will always use the number.
  - * * When given a function, the service will invoke the function every time it restores scroll
  - * position.
  */
  setOffset(offset: [number, number]|(() => [number, number])): void {
  if (Array.isArray(offset)) {
  @@ -80,7 +79,8 @@ export class BrowserViewportScroller implements ViewportScroller {
  }
  /**
  - * Returns the current scroll position.
  + * Retrieves the current scroll position.
  + * @returns The position in screen coordinates.
  */
  getScrollPosition(): [number, number] {
  if (this.supportScrollRestoration()) {
  @@ -92,6 +92,7 @@ export class BrowserViewportScroller implements ViewportScroller {
  /**
  * Sets the scroll position.
  + * @param position The new position in screen coordinates.
  */
  scrollToPosition(position: [number, number]): void {
  if (this.supportScrollRestoration()) {
  @@ -100,7 +101,8 @@ export class BrowserViewportScroller implements ViewportScroller {
  }
  /**
  - * Scrolls to the provided anchor.
  + * Scrolls to an anchor element.
  + * @param anchor The ID of the anchor element.
  */
  scrollToAnchor(anchor: string): void {
  if (this.supportScrollRestoration()) {
  