resource: remove slow element ratio (ser) (#30972)

extensions/amp-viewer-integration/TICKEVENTS.md

@@ -53,4 +53,3 @@ As an example if we executed `perf.tick('label')` we assume we have a counterpar
 | Load Event Start                         | `loadEventStart`             | Time immediately before the load event of the current document is fired                                                                                                                            |
 | Request Start                            | `requestStart`               | Time immediately before the user agent starts requesting the resource from the server                                                                                                              |
 | Response Start                           | `responseStart`              | Time immediately after the user agent's HTTP parser receives the first byte of the response from the server                                                                                        |
-| Slow element ratio                       | `ser`                        | Percentage of elements laid out after entering viewport                                                                                                                                            |

src/enums.js

@@ -55,7 +55,6 @@ export const TickLabel = {
   MESSAGING_READY: 'msr',
   ON_FIRST_VISIBLE: 'ofv',
   ON_LOAD: 'ol',
-  SLOW_ELEMENT_RATIO: 'ser',
   TIME_ORIGIN: 'timeOrigin',
   VIDEO_CACHE_STATE: 'vcs',
   VIDEO_ERROR: 'verr',

src/inabox/inabox-resources.js

@@ -256,11 +256,6 @@ export class InaboxResources {
       observer.observe(element);
     }
   }
-
-  /** @override */
-  getSlowElementRatio() {
-    return 0;
-  }
 }
 
 /**

src/service/performance-impl.js

@@ -114,12 +114,6 @@ export class Performance {
      */
     this.aggregateShiftScore_ = 0;
 
-    /**
-     * True if the ratios have already been ticked.
-     * @private {boolean}
-     */
-    this.slowElementRatioTicked_ = false;
-
     const supportedEntryTypes =
       (this.win.PerformanceObserver &&
         this.win.PerformanceObserver.supportedEntryTypes) ||
@@ -503,7 +497,6 @@ export class Performance {
     if (this.supportsLargestContentfulPaint_) {
       this.tickLargestContentfulPaint_();
     }
-    this.tickSlowElementRatio_();
   }
 
   /**
@@ -543,26 +536,6 @@ export class Performance {
     }
   }
 
-  /**
-   * Tick the slow element ratio.
-   */
-  tickSlowElementRatio_() {
-    if (this.slowElementRatioTicked_) {
-      return;
-    }
-    if (!this.resources_) {
-      dev().error(TAG, 'Failed to tick ser due to null resources');
-      return;
-    }
-
-    this.slowElementRatioTicked_ = true;
-    this.tickDelta(
-      TickLabel.SLOW_ELEMENT_RATIO,
-      this.resources_.getSlowElementRatio()
-    );
-    this.flush();
-  }
-
   /**
    * Tick fp time based on Chromium's legacy paint timing API when
    * appropriate.

src/service/resources-impl.js

@@ -208,18 +208,6 @@ export class ResourcesImpl {
       this.ampdoc.getVisibilityState()
     );
 
-    /**
-     * Number of resources that were laid out after entering viewport.
-     * @private {number}
-     */
-    this.slowLayoutCount_ = 0;
-
-    /**
-     * Total number of laid out resources.
-     * @private {number}
-     */
-    this.totalLayoutCount_ = 0;
-
     /** @private {?IntersectionObserver} */
     this.intersectionObserver_ = null;
 
@@ -833,14 +821,6 @@ export class ResourcesImpl {
     }
   }
 
-  /** @override */
-  getSlowElementRatio() {
-    if (this.totalLayoutCount_ === 0) {
-      return 0;
-    }
-    return this.slowLayoutCount_ / this.totalLayoutCount_;
-  }
-
   /**
    * Returns `true` when there's mutate work currently batched.
    * @return {boolean}
@@ -1671,11 +1651,6 @@ export class ResourcesImpl {
    * @private
    */
   taskComplete_(task, success, opt_reason) {
-    this.totalLayoutCount_++;
-    if (task.resource.isInViewport() && this.firstVisibleTime_ >= 0) {
-      this.slowLayoutCount_++;
-    }
-
     this.exec_.dequeue(task);
     this.schedulePass(POST_TASK_PASS_DELAY_);
     if (!success) {

src/service/resources-interface.js

@@ -183,11 +183,5 @@ export class ResourcesInterface {
    * @return {boolean}
    */
   isIntersectionExperimentOn() {}
-
-  /**
-   * Returns the percent of resources that were laid out after entering viewport.
-   * @return {number}
-   */
-  getSlowElementRatio() {}
 }
 /* eslint-enable no-unused-vars */

test/unit/test-resources.js

@@ -463,43 +463,6 @@ describe('Resources', () => {
     // The other task is not updated.
     expect(task2.priority).to.equal(LayoutPriority.ADS);
   });
-
-  describe('slow element ratio (ser)', () => {
-    const slowTask = {resource: {isInViewport: () => true}};
-    const fastTask = {resource: {isInViewport: () => false}};
-
-    it('No layouts --> 0', () => {
-      resources.firstVisibleTime_ = 1;
-      expect(resources.getSlowElementRatio()).equal(0);
-    });
-
-    it('0 slow / 1 total --> 0', () => {
-      resources.firstVisibleTime_ = 1;
-      resources.taskComplete_(fastTask);
-      expect(resources.getSlowElementRatio()).equal(0);
-    });
-
-    it('ser is 0 if page was never visible', () => {
-      resources.firstVisibleTime_ = -1;
-      resources.taskComplete_(slowTask);
-      expect(resources.getSlowElementRatio()).equal(0);
-    });
-
-    it('1 slow / 1 total --> 1', () => {
-      resources.firstVisibleTime_ = 1;
-      resources.taskComplete_(slowTask);
-      expect(resources.getSlowElementRatio()).equal(1);
-    });
-
-    it('9 slow/ 10 total --> 0.9', () => {
-      resources.firstVisibleTime_ = 1;
-      for (let i = 0; i < 9; i++) {
-        resources.taskComplete_(slowTask);
-      }
-      resources.taskComplete_(fastTask);
-      expect(resources.getSlowElementRatio()).equal(0.9);
-    });
-  });
 });
 
 describes.fakeWin(