Prevent site engagement scores from decaying when Chrome isn't in use.

chrome/browser/engagement/site_engagement_score.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/engagement/site_engagement_score.h"
 
 #include <cmath>
 
 #include "base/memory/ptr_util.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 24 matching lines @@
     "decay_period_in_days",
     "decay_points",
     "navigation_points",
     "user_input_points",
     "visible_media_playing_points",
     "hidden_media_playing_points",
     "web_app_installed_points",
     "first_daily_engagement_points",
     "medium_engagement_boundary",
     "high_engagement_boundary",
+    "max_decays_per_score",
+    "last_engagement_grace_period_in_hours",
 };
 
 bool DoublesConsideredDifferent(double value1, double value2, double delta) {
   double abs_difference = fabs(value1 - value2);
   return abs_difference > delta;
 }
 
 std::unique_ptr<base::DictionaryValue> GetScoreDictForOrigin(
     HostContentSettingsMap* settings,
     const GURL& origin_url) {
@@ skipping 21 matching lines @@
     5,     // DECAY_POINTS
     0.5,   // NAVIGATION_POINTS
     0.2,   // USER_INPUT_POINTS
     0.02,  // VISIBLE_MEDIA_POINTS
     0.01,  // HIDDEN_MEDIA_POINTS
     5,     // WEB_APP_INSTALLED_POINTS
     0.5,   // FIRST_DAILY_ENGAGEMENT
     8,     // BOOTSTRAP_POINTS
     5,     // MEDIUM_ENGAGEMENT_BOUNDARY
     50,    // HIGH_ENGAGEMENT_BOUNDARY
+    1,     // MAX_DECAYS_PER_SCORE
+    72,    // LAST_ENGAGEMENT_GRACE_PERIOD_IN_HOURS
 };
 
 const char* SiteEngagementScore::kRawScoreKey = "rawScore";
 const char* SiteEngagementScore::kPointsAddedTodayKey = "pointsAddedToday";
 const char* SiteEngagementScore::kLastEngagementTimeKey = "lastEngagementTime";
 const char* SiteEngagementScore::kLastShortcutLaunchTimeKey =
     "lastShortcutLaunchTime";
 
 double SiteEngagementScore::GetMaxPointsPerDay() {
   return param_values[MAX_POINTS_PER_DAY];
@@ skipping 36 matching lines @@
 }
 
 double SiteEngagementScore::GetMediumEngagementBoundary() {
   return param_values[MEDIUM_ENGAGEMENT_BOUNDARY];
 }
 
 double SiteEngagementScore::GetHighEngagementBoundary() {
   return param_values[HIGH_ENGAGEMENT_BOUNDARY];
 }
 
+double SiteEngagementScore::GetMaxDecaysPerScore() {
+  return param_values[MAX_DECAYS_PER_SCORE];
+}
+
+double SiteEngagementScore::GetLastEngagementGracePeriodInHours() {
+  return param_values[LAST_ENGAGEMENT_GRACE_PERIOD_IN_HOURS];
+}
+
 // static
 void SiteEngagementScore::UpdateFromVariations(const char* param_name) {
   double param_vals[MAX_VARIATION];
 
   for (int i = 0; i < MAX_VARIATION; ++i) {
     std::string param_string =
         variations::GetVariationParamValue(param_name, kVariationNames[i]);
 
     // Bail out if we didn't get a param string for the key, or if we couldn't
     // convert the param string to a double, or if we get a negative value.
@@ skipping 178 matching lines @@
   param_values[DECAY_PERIOD_IN_DAYS] = 7;
   param_values[DECAY_POINTS] = 5;
   param_values[NAVIGATION_POINTS] = 0.5;
   param_values[USER_INPUT_POINTS] = 0.05;
   param_values[VISIBLE_MEDIA_POINTS] = 0.02;
   param_values[HIDDEN_MEDIA_POINTS] = 0.01;
   param_values[WEB_APP_INSTALLED_POINTS] = 5;
   param_values[BOOTSTRAP_POINTS] = 8;
   param_values[MEDIUM_ENGAGEMENT_BOUNDARY] = 5;
   param_values[HIGH_ENGAGEMENT_BOUNDARY] = 50;
+  param_values[MAX_DECAYS_PER_SCORE] = 1;
+  param_values[LAST_ENGAGEMENT_GRACE_PERIOD_IN_HOURS] = 72;
 
   // This is set to zero to avoid interference with tests and is set when
   // testing this functionality.
   param_values[FIRST_DAILY_ENGAGEMENT] = 0;
 }