[Media Engagement] Remove histogram

Remove the ScoreAtStartup histogram as it was causing
jank and we were not using it.

BUG=900679

Change-Id: I004743c48425c9bb3fbbed67004c7616ef290cf9
Reviewed-on: https://chromium-review.googlesource.com/c/1330211
Commit-Queue: Becca Hughes <beccahughes@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Brian White <bcwhite@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607751}

chrome/browser/media/media_engagement_service.cc

@@ -23,9 +23,6 @@
 #include "content/public/browser/web_contents.h"
 #include "media/base/media_switches.h"
 
-const char MediaEngagementService::kHistogramScoreAtStartupName[] =
-    "Media.Engagement.ScoreAtStartup";
-
 const char MediaEngagementService::kHistogramURLsDeletedScoreReductionName[] =
     "Media.Engagement.URLsDeletedScoreReduction";
 
@@ -142,18 +139,9 @@ MediaEngagementService::MediaEngagementService(Profile* profile,
         ->ClearSettingsForOneType(CONTENT_SETTINGS_TYPE_MEDIA_ENGAGEMENT);
     SetSchemaVersion(kSchemaVersion);
   }
-
-  // Record the stored scores to a histogram.
-  task_tracker_.PostTask(
-      base::ThreadTaskRunnerHandle::Get().get(), FROM_HERE,
-      base::BindOnce(&MediaEngagementService::RecordStoredScoresToHistogram,
-                     base::Unretained(this)));
 }
 
-MediaEngagementService::~MediaEngagementService() {
-  // Cancel any tasks that depend on |this|.
-  task_tracker_.TryCancelAll();
-}
+MediaEngagementService::~MediaEngagementService() = default;
 
 int MediaEngagementService::GetSchemaVersion() const {
   return profile_->GetPrefs()->GetInteger(prefs::kMediaEngagementSchemaVersion);
@@ -187,14 +175,6 @@ void MediaEngagementService::Shutdown() {
     history->RemoveObserver(this);
 }
 
-void MediaEngagementService::RecordStoredScoresToHistogram() {
-  for (const MediaEngagementScore& score : GetAllStoredScores()) {
-    int percentage = round(score.actual_score() * 100);
-    UMA_HISTOGRAM_PERCENTAGE(
-        MediaEngagementService::kHistogramScoreAtStartupName, percentage);
-  }
-}
-
 void MediaEngagementService::OnURLsDeleted(
     history::HistoryService* history_service,
     const history::DeletionInfo& deletion_info) {

chrome/browser/media/media_engagement_service.h

@@ -9,7 +9,6 @@
 #include <set>
 
 #include "base/macros.h"
-#include "base/task/cancelable_task_tracker.h"
 #include "base/values.h"
 #include "chrome/browser/media/media_engagement_score.h"
 #include "chrome/browser/media/media_engagement_score_details.mojom.h"
@@ -89,9 +88,6 @@ class MediaEngagementService : public KeyedService,
 
   Profile* profile() const;
 
-  // The name of the histogram that scores are logged to on startup.
-  static const char kHistogramScoreAtStartupName[];
-
   // The name of the histogram that records the reduction in score when history
   // is cleared.
   static const char kHistogramURLsDeletedScoreReductionName[];
@@ -126,9 +122,6 @@ class MediaEngagementService : public KeyedService,
   // An internal clock for testing.
   base::Clock* clock_;
 
-  // Records all the stored scores to a histogram.
-  void RecordStoredScoresToHistogram();
-
   std::vector<MediaEngagementScore> GetAllStoredScores() const;
 
   int GetSchemaVersion() const;
@@ -141,9 +134,6 @@ class MediaEngagementService : public KeyedService,
       const std::set<GURL>& deleted_origins,
       const history::OriginCountAndLastVisitMap& origin_data);
 
-  // Allows us to cancel the RecordScoresToHistogram task if we are destroyed.
-  base::CancelableTaskTracker task_tracker_;
-
   DISALLOW_COPY_AND_ASSIGN(MediaEngagementService);
 };
 

chrome/browser/media/media_engagement_service_unittest.cc

@@ -817,35 +817,6 @@ TEST_F(MediaEngagementServiceTest, CleanupDataOnSiteDataCleanup_NoTimeSet) {
       MediaEngagementService::kHistogramClearName, 1, 1);
 }
 
-TEST_F(MediaEngagementServiceTest, LogScoresOnStartupToHistogram) {
-  GURL url1("https://www.google.com");
-  GURL url2("https://www.google.co.uk");
-  GURL url3("https://www.example.com");
-
-  SetScores(url1, 24, 20);
-  SetScores(url2, 24, 12);
-  RecordVisitAndPlaybackAndAdvanceClock(url3);
-
-  ExpectScores(url1, 5.0 / 6.0, 24, 20, TimeNotSet());
-  ExpectScores(url2, 0.5, 24, 12, TimeNotSet());
-  ExpectScores(url3, 0.05, 1, 1, Now());
-
-  base::HistogramTester histogram_tester;
-  std::unique_ptr<MediaEngagementService> new_service =
-      base::WrapUnique<MediaEngagementService>(
-          StartNewMediaEngagementService());
-  new_service->Shutdown();
-
-  histogram_tester.ExpectTotalCount(
-      MediaEngagementService::kHistogramScoreAtStartupName, 3);
-  histogram_tester.ExpectBucketCount(
-      MediaEngagementService::kHistogramScoreAtStartupName, 5, 1);
-  histogram_tester.ExpectBucketCount(
-      MediaEngagementService::kHistogramScoreAtStartupName, 50, 1);
-  histogram_tester.ExpectBucketCount(
-      MediaEngagementService::kHistogramScoreAtStartupName, 83, 1);
-}
-
 TEST_F(MediaEngagementServiceTest, CleanupDataOnSiteDataCleanup_All) {
   GURL origin1("https://www.google.com");
   GURL origin2("https://www.google.co.uk");

tools/metrics/histograms/histograms.xml

@@ -45371,6 +45371,9 @@ uploading your change for review.
 </histogram>
 
 <histogram name="Media.Engagement.ScoreAtStartup" units="%">
+  <obsolete>
+    Deprecated 11/2018 in Issue 900679 as we are no longer using this.
+  </obsolete>
   <owner>beccahughes@chromium.org</owner>
   <owner>media-dev@chromium.org</owner>
   <summary>