[subresource_filter] Use the SubresourceFilterObserver for PageLoadMetrics

chrome/browser/page_load_metrics/observers/subresource_filter_metrics_observer.cc

 // Copyright 2017 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/subresource_filter_metrics_observer.h"
 
 #include "chrome/browser/page_load_metrics/page_load_metrics_util.h"
 #include "components/subresource_filter/content/browser/content_subresource_filter_driver_factory.h"
 #include "components/subresource_filter/core/common/activation_decision.h"
 #include "third_party/WebKit/public/platform/WebLoadingBehaviorFlag.h"
@@ skipping 117 matching lines @@
           navigation_handle->GetPageTransition())) {
     UMA_HISTOGRAM_ENUMERATION(
         internal::kHistogramSubresourceFilterActivationDecisionReload,
         static_cast<int>(decision),
         static_cast<int>(ActivationDecision::ACTIVATION_DECISION_MAX));
   }
 }
 
 }  // namespace
 
+SubresourceFilterMetricsObserver::SubresourceFilterMetricsObserver()
+    : scoped_observer_(this) {}
+SubresourceFilterMetricsObserver::~SubresourceFilterMetricsObserver() = default;
+
 page_load_metrics::PageLoadMetricsObserver::ObservePolicy
 SubresourceFilterMetricsObserver::FlushMetricsOnAppEnterBackground(
     const page_load_metrics::mojom::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info) {
   // FlushMetricsOnAppEnterBackground is invoked on Android in cases where the
   // app is about to be backgrounded, as part of the Activity.onPause()
   // flow. After this method is invoked, Chrome may be killed without further
   // notification, so we record final metrics collected up to this point.
   if (info.did_commit)
     OnGoingAway(timing, info, base::TimeTicks::Now());
   return STOP_OBSERVING;
 }
+page_load_metrics::PageLoadMetricsObserver::ObservePolicy
+SubresourceFilterMetricsObserver::OnStart(
+    content::NavigationHandle* navigation_handle,
+    const GURL& currently_committed_url,
+    bool started_in_foreground) {
+  auto* observer_manager =
+      subresource_filter::SubresourceFilterObserverManager::FromWebContents(
+          navigation_handle->GetWebContents());
+  if (observer_manager)

[Bryan McQuade, 2017/05/23 19:31:57]

what are the cases where observer manager won't exist? will it not exist if
filtering is disabled for instance?

[Charlie Harrison, 2017/05/23 19:58:50]

Only tests :/ I can add a comment.

+    scoped_observer_.Add(observer_manager);
+  return CONTINUE_OBSERVING;
+}
 
 page_load_metrics::PageLoadMetricsObserver::ObservePolicy
 SubresourceFilterMetricsObserver::OnCommit(

[Bryan McQuade, 2017/05/23 19:31:57]

i think we discussed this, but the activation decision will have always been
reported before commit, is that right?

is there any way we can audit this? perhaps if we're registered as a listener,
we can dcheck that activation_decision_.has_value()?

[Charlie Harrison, 2017/05/23 19:58:50]

Done.

     content::NavigationHandle* navigation_handle) {
-  const auto* subres_filter =
-      ContentSubresourceFilterDriverFactory::FromWebContents(
-          navigation_handle->GetWebContents());
-  if (subres_filter)
-    LogActivationDecisionMetrics(
-        navigation_handle,
-        subres_filter->GetActivationDecisionForLastCommittedPageLoad());
+  if (activation_decision_)
+    LogActivationDecisionMetrics(navigation_handle, *activation_decision_);
   return CONTINUE_OBSERVING;
 }
 
 void SubresourceFilterMetricsObserver::OnComplete(
     const page_load_metrics::mojom::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info) {
   OnGoingAway(timing, info, base::TimeTicks());
 }
 
 void SubresourceFilterMetricsObserver::OnLoadedResource(
@@ skipping 119 matching lines @@
     UMA_HISTOGRAM_BOOLEAN(internal::kHistogramSubresourceFilterCount, true);
   }
 }
 
 void SubresourceFilterMetricsObserver::MediaStartedPlaying(
     const content::WebContentsObserver::MediaPlayerInfo& video_type,
     bool is_in_main_frame) {
   played_media_ = true;
 }
 
+void SubresourceFilterMetricsObserver::OnPageActivationComputed(
+    content::NavigationHandle* navigation_handle,
+    subresource_filter::ActivationDecision activation_decision,
+    const subresource_filter::ActivationState& activation_state) {
+  activation_decision_ = activation_decision;
+}
+
 void SubresourceFilterMetricsObserver::OnGoingAway(
     const page_load_metrics::mojom::PageLoadTiming& timing,
     const page_load_metrics::PageLoadExtraInfo& info,
     base::TimeTicks app_background_time) {
   if (!subresource_filter_observed_)
     return;
 
   PAGE_RESOURCE_COUNT_HISTOGRAM(
       internal::kHistogramSubresourceFilterNetworkResources,
       num_network_resources_);
@@ skipping 56 matching lines @@
         foreground_duration.value());
     if (timing.paint_timing->first_paint &&
         timing.paint_timing->first_paint < foreground_duration) {
       PAGE_LOAD_LONG_HISTOGRAM(
           internal::kHistogramSubresourceFilterForegroundDurationAfterPaint,
           foreground_duration.value() -
               timing.paint_timing->first_paint.value());
     }
   }
 }