🐛 amp-story: Remove duplicate replaceState on navigation (ampproject#26624)

* throttle replaceState and get rid of page_id usage

* fix test

* move throttle to amp-story

* apply throttle to all replace

* use history buffer

* make caller provide own throttle

* clear settimeout after each test

* Revert "make caller provide own throttle"

This reverts commit 7213df4.

* remove throttle

Author: Enriqe

extensions/amp-story/1.0/amp-story.js

@@ -104,7 +104,7 @@ import {dev, devAssert, user} from '../../../src/log';
 import {dict, map} from '../../../src/utils/object';
 import {endsWith} from '../../../src/string';
 import {escapeCssSelectorIdent} from '../../../src/css';
-import {findIndex} from '../../../src/utils/array';
+import {findIndex, lastItem} from '../../../src/utils/array';
 import {getConsentPolicyState} from '../../../src/consent';
 import {getDetail} from '../../../src/event-helper';
 import {getMediaQueryService} from './amp-story-media-query-service';
@@ -738,10 +738,6 @@ export class AmpStory extends AMP.BaseElement {
       this.onBookendStateUpdate_(isActive);
     });
 
-    this.storeService_.subscribe(StateProperty.CURRENT_PAGE_ID, pageId => {
-      this.onCurrentPageIdUpdate_(pageId);
-    });
-
     this.storeService_.subscribe(StateProperty.PAUSED_STATE, isPaused => {
       this.onPausedStateUpdate_(isPaused);
     });
@@ -1068,16 +1064,17 @@ export class AmpStory extends AMP.BaseElement {
    * @private
    */
   getInitialPageId_(firstPageEl) {
-    const historyPage = /** @type {string} */ (getHistoryState(
-      this.win,
-      HistoryState.PAGE_ID
-    ));
-
     const maybePageId = parseQueryString(this.win.location.hash)['page'];
     if (maybePageId && this.isActualPage_(maybePageId)) {
       return maybePageId;
     }
 
+    const pages =
+      /**  @type {!Array} */ (getHistoryState(
+        this.win,
+        HistoryState.NAVIGATION_PATH
+      ) || []);
+    const historyPage = lastItem(pages);
     if (historyPage && this.isActualPage_(historyPage)) {
       return historyPage;
     }
@@ -1682,20 +1679,6 @@ export class AmpStory extends AMP.BaseElement {
     }
   }
 
-  /**
-   * @param {string} pageId new current page id
-   * @private
-   * */
-  onCurrentPageIdUpdate_(pageId) {
-    // Never save ad pages to history as they are unique to each visit.
-    const page = this.getPageById(pageId);
-    if (page.isAd()) {
-      return;
-    }
-
-    setHistoryState(this.win, HistoryState.PAGE_ID, pageId);
-  }
-
   /**
    * Handle resize events and set the story's desktop state.
    * @visibleForTesting

extensions/amp-story/1.0/test/test-amp-story.js

@@ -352,7 +352,7 @@ describes.realWin(
 
       await story.layoutCallback();
       expect(replaceStateStub).to.have.been.calledWith(
-        {ampStoryPageId: firstPageId},
+        {ampStoryNavigationPath: [firstPageId]},
         ''
       );
     });

extensions/amp-story/1.0/utils.js

@@ -256,7 +256,6 @@ export function resolveImgSrc(win, url) {
 export const HistoryState = {
   ATTACHMENT_PAGE_ID: 'ampStoryAttachmentPageId',
   BOOKEND_ACTIVE: 'ampStoryBookendActive',
-  PAGE_ID: 'ampStoryPageId',
   NAVIGATION_PATH: 'ampStoryNavigationPath',
 };