Remove CssScanning PLMO

The CSS scanning optimization has been removed, so these metrics
aren't being recorded anymore.

Bug: None
Change-Id: I4f10216e45962c4c75c440518a1f13721e684361
Reviewed-on: https://chromium-review.googlesource.com/1222626Reviewed-by: Bryan McQuade <bmcquade@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Commit-Queue: Charlie Harrison <csharrison@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591393}

chrome/browser/BUILD.gn

@@ -926,8 +926,6 @@ jumbo_split_static_library("browser") {
     "page_load_metrics/observers/amp_page_load_metrics_observer.h",
     "page_load_metrics/observers/core_page_load_metrics_observer.cc",
     "page_load_metrics/observers/core_page_load_metrics_observer.h",
-    "page_load_metrics/observers/css_scanning_page_load_metrics_observer.cc",
-    "page_load_metrics/observers/css_scanning_page_load_metrics_observer.h",
     "page_load_metrics/observers/data_reduction_proxy_metrics_observer.cc",
     "page_load_metrics/observers/data_reduction_proxy_metrics_observer.h",
     "page_load_metrics/observers/data_saver_site_breakdown_metrics_observer.cc",

chrome/browser/page_load_metrics/observers/css_scanning_page_load_metrics_observer.cc

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "chrome/browser/page_load_metrics/observers/css_scanning_page_load_metrics_observer.h"
-
-#include "chrome/browser/page_load_metrics/page_load_metrics_util.h"
-#include "third_party/blink/public/platform/web_loading_behavior_flag.h"
-
-CssScanningMetricsObserver::CssScanningMetricsObserver() {}
-
-CssScanningMetricsObserver::~CssScanningMetricsObserver() {}
-
-void CssScanningMetricsObserver::OnLoadingBehaviorObserved(
-    const page_load_metrics::PageLoadExtraInfo& info) {
-  if (css_preload_found_)
-    return;
-
-  css_preload_found_ = page_load_metrics::DidObserveLoadingBehaviorInAnyFrame(
-      info, blink::WebLoadingBehaviorFlag::kWebLoadingBehaviorCSSPreloadFound);
-}
-
-page_load_metrics::PageLoadMetricsObserver::ObservePolicy
-CssScanningMetricsObserver::OnStart(
-    content::NavigationHandle* navigation_handle,
-    const GURL& currently_committed_url,
-    bool started_in_foreground) {
-  return started_in_foreground ? CONTINUE_OBSERVING : STOP_OBSERVING;
-}
-
-page_load_metrics::PageLoadMetricsObserver::ObservePolicy
-CssScanningMetricsObserver::OnHidden(
-    const page_load_metrics::mojom::PageLoadTiming&,
-    const page_load_metrics::PageLoadExtraInfo&) {
-  return STOP_OBSERVING;
-}
-
-void CssScanningMetricsObserver::OnFirstContentfulPaintInPage(
-    const page_load_metrics::mojom::PageLoadTiming& timing,
-    const page_load_metrics::PageLoadExtraInfo& info) {
-  if (!css_preload_found_)
-    return;
-
-  PAGE_LOAD_HISTOGRAM(
-      "PageLoad.Clients.CssScanner.PaintTiming."
-      "ParseStartToFirstContentfulPaint",
-      timing.paint_timing->first_contentful_paint.value() -
-          timing.parse_timing->parse_start.value());
-}
-
-void CssScanningMetricsObserver::OnFirstMeaningfulPaintInMainFrameDocument(
-    const page_load_metrics::mojom::PageLoadTiming& timing,
-    const page_load_metrics::PageLoadExtraInfo& info) {
-  if (!css_preload_found_)
-    return;
-
-  PAGE_LOAD_HISTOGRAM(
-      "PageLoad.Clients.CssScanner.Experimental.PaintTiming."
-      "ParseStartToFirstMeaningfulPaint",
-      timing.paint_timing->first_meaningful_paint.value() -
-          timing.parse_timing->parse_start.value());
-}

chrome/browser/page_load_metrics/observers/css_scanning_page_load_metrics_observer.h

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_CSS_SCANNING_PAGE_LOAD_METRICS_OBSERVER_H_
-#define CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_CSS_SCANNING_PAGE_LOAD_METRICS_OBSERVER_H_
-
-#include "base/macros.h"
-#include "chrome/browser/page_load_metrics/page_load_metrics_observer.h"
-
-class CssScanningMetricsObserver
-    : public page_load_metrics::PageLoadMetricsObserver {
- public:
-  CssScanningMetricsObserver();
-  ~CssScanningMetricsObserver() override;
-
-  // page_load_metrics::PageLoadMetricsObserver:
-  ObservePolicy OnStart(content::NavigationHandle* navigation_handle,
-                        const GURL& currently_committed_url,
-                        bool started_in_foreground) override;
-  ObservePolicy OnHidden(
-      const page_load_metrics::mojom::PageLoadTiming& timing,
-      const page_load_metrics::PageLoadExtraInfo& info) override;
-  void OnLoadingBehaviorObserved(
-      const page_load_metrics::PageLoadExtraInfo& info) override;
-  void OnFirstContentfulPaintInPage(
-      const page_load_metrics::mojom::PageLoadTiming& timing,
-      const page_load_metrics::PageLoadExtraInfo& info) override;
-  void OnFirstMeaningfulPaintInMainFrameDocument(
-      const page_load_metrics::mojom::PageLoadTiming& timing,
-      const page_load_metrics::PageLoadExtraInfo& info) override;
-
- private:
-  bool css_preload_found_ = false;
-
-  DISALLOW_COPY_AND_ASSIGN(CssScanningMetricsObserver);
-};
-
-#endif  // CHROME_BROWSER_PAGE_LOAD_METRICS_OBSERVERS_CSS_SCANNING_PAGE_LOAD_METRICS_OBSERVER_H_

chrome/browser/page_load_metrics/page_load_metrics_initialize.cc

@@ -15,7 +15,6 @@
 #include "chrome/browser/page_load_metrics/observers/ads_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/amp_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/core_page_load_metrics_observer.h"
-#include "chrome/browser/page_load_metrics/observers/css_scanning_page_load_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/data_reduction_proxy_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/data_saver_site_breakdown_metrics_observer.h"
 #include "chrome/browser/page_load_metrics/observers/document_write_page_load_metrics_observer.h"
@@ -121,7 +120,6 @@ void PageLoadMetricsEmbedder::RegisterObservers(
     tracker->AddObserver(
         std::make_unique<HttpsEngagementPageLoadMetricsObserver>(
             web_contents_->GetBrowserContext()));
-    tracker->AddObserver(std::make_unique<CssScanningMetricsObserver>());
     tracker->AddObserver(std::make_unique<ProtocolPageLoadMetricsObserver>());
     tracker->AddObserver(std::make_unique<TabRestorePageLoadMetricsObserver>());
     tracker->AddObserver(std::make_unique<UseCounterPageLoadMetricsObserver>());

tools/metrics/histograms/histograms.xml

@@ -127043,6 +127043,9 @@ uploading your change for review.
 
 <histogram_suffixes name="PageLoadMetricsClientsCssScanner" separator="."
     ordering="prefix">
+  <obsolete>
+    Deprecated September 2018
+  </obsolete>
   <suffix name="Clients.CssScanner"
       label="Metrics from pages scanned by the preload scanner for @import
              CSS rules"/>