Media Engagement: better handling of history service callbacks.

- When all history is cleared, simply wipe all of MEI data instead of
  handling it per website.
- When history is expired, do nothing. Better handling of this event
  will be implemented as par tof bug 818153

Bug: 815163
Change-Id: I87c5d3e91b4c4e0c3191bb3c4e9c889ac6830790
Reviewed-on: https://chromium-review.googlesource.com/946169
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540842}

chrome/browser/media/media_engagement_service.cc

@@ -29,12 +29,24 @@ const char MediaEngagementService::kHistogramScoreAtStartupName[] =
 const char MediaEngagementService::kHistogramURLsDeletedScoreReductionName[] =
     "Media.Engagement.URLsDeletedScoreReduction";
 
+const char MediaEngagementService::kHistogramClearName[] =
+    "Media.Engagement.Clear";
+
 namespace {
 
 // The current schema version of the MEI data. If this value is higher
 // than the stored value, all MEI data will be wiped.
 static const int kSchemaVersion = 4;
 
+// Do not change the values of this enum as it is used for UMA.
+enum class MediaEngagementClearReason {
+  kDataAll = 0,
+  kDataRange = 1,
+  kHistoryAll = 2,
+  kHistoryRange = 3,
+  kCount
+};
+
 bool MediaEngagementFilterAdapter(
     const GURL& predicate,
     const ContentSettingsPattern& primary_pattern,
@@ -66,6 +78,11 @@ void RecordURLsDeletedScoreReduction(double previous_score,
       difference);
 }
 
+void RecordClear(MediaEngagementClearReason reason) {
+  UMA_HISTOGRAM_ENUMERATION(MediaEngagementService::kHistogramClearName, reason,
+                            MediaEngagementClearReason::kCount);
+}
+
 }  // namespace
 
 // static
@@ -149,6 +166,11 @@ void MediaEngagementService::SetSchemaVersion(int version) {
 void MediaEngagementService::ClearDataBetweenTime(
     const base::Time& delete_begin,
     const base::Time& delete_end) {
+  if (delete_begin == base::Time() && delete_end == base::Time::Max())
+    RecordClear(MediaEngagementClearReason::kDataAll);
+  else
+    RecordClear(MediaEngagementClearReason::kDataRange);
+
   HostContentSettingsMapFactory::GetForProfile(profile_)
       ->ClearSettingsForOneTypeWithPredicate(
           CONTENT_SETTINGS_TYPE_MEDIA_ENGAGEMENT, base::Time(),
@@ -177,6 +199,19 @@ void MediaEngagementService::OnURLsDeleted(
     bool expired,
     const history::URLRows& deleted_rows,
     const std::set<GURL>& favicon_urls) {
+  if (all_history) {
+    RecordClear(MediaEngagementClearReason::kHistoryAll);
+
+    HostContentSettingsMapFactory::GetForProfile(profile_)
+        ->ClearSettingsForOneType(CONTENT_SETTINGS_TYPE_MEDIA_ENGAGEMENT);
+    return;
+  }
+
+  // TODO(818153): history expiration currently has no effect on MEI but entries
+  // that no longer appear in history should be removed from the database.
+  if (expired)
+    return;
+
   std::map<GURL, int> origins;
   for (const history::URLRow& row : deleted_rows) {
     GURL origin = row.url().GetOrigin();
@@ -186,6 +221,9 @@ void MediaEngagementService::OnURLsDeleted(
     origins[origin]++;
   }
 
+  if (!origins.empty())
+    RecordClear(MediaEngagementClearReason::kHistoryRange);
+
   for (auto const& kv : origins) {
     // Remove the number of visits consistent with the number
     // of URLs from the same origin we are removing.

chrome/browser/media/media_engagement_service.h

@@ -102,6 +102,10 @@ class MediaEngagementService : public KeyedService,
   // is cleared.
   static const char kHistogramURLsDeletedScoreReductionName[];
 
+  // The name of the histogram that records the reason why the engagement was
+  // cleared, either partially or fully.
+  static const char kHistogramClearName[];
+
  private:
   friend class MediaEngagementBrowserTest;
   friend class MediaEngagementContentsObserverTest;

tools/metrics/histograms/enums.xml

@@ -28536,6 +28536,13 @@ Called by update_use_counter_css.py.-->
   <int value="21" label="Gesture requirement overridden by play method."/>
 </enum>
 
+<enum name="MediaEngagementClearReason">
+  <int value="0" label="Data (all)"/>
+  <int value="1" label="Data (range)"/>
+  <int value="2" label="History (all)"/>
+  <int value="3" label="History (range)"/>
+</enum>
+
 <enum name="MediaEngagementSessionEvent">
   <int value="0" label="Created"/>
   <int value="1" label="Significant Playback"/>

tools/metrics/histograms/histograms.xml

@@ -35372,6 +35372,15 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Media.Engagement.Clear" enum="MediaEngagementClearReason">
+  <owner>mlamouri@chromium.org</owner>
+  <owner>media-dev@chromium.org</owner>
+  <summary>
+    Records the reason why the Media Engagement data was cleared. Partial
+    changes and full wipeout will both be recorded as one event.
+  </summary>
+</histogram>
+
 <histogram name="Media.Engagement.PreloadedList.CheckResult"
     enum="PreloadedListCheckResult">
   <owner>beccahughes@chromium.org</owner>