Update Tab Ranker model.

(1) Update native_inference.h, native_inference.cc,
example_preprocessor_config.pb to be the newest model.

(2) Update tab_score_predictor_unittest.cc

(3) Add amoylan as extra owner of this directory.

Change-Id: Iffb2f84e5cbf65ae20d864fccc2edface051055e
Reviewed-on: https://chromium-review.googlesource.com/1068952
Commit-Queue: Charles . <charleszhao@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#561352}

chrome/browser/resource_coordinator/tab_ranker/OWNERS

 set noparent
+amoylan@chromium.org
 michaelpg@chromium.org

chrome/browser/resource_coordinator/tab_ranker/native_inference.h

@@ -14,9 +14,9 @@
 namespace tab_ranker {
 namespace tfnative_model {
 
-constexpr int DNN_WEIGHTS_SIZE = 29040;
+constexpr int DNN_WEIGHTS_SIZE = 29160;
 constexpr int DNN_RANK = 2;
-constexpr int FEATURES_SIZE = 726;
+constexpr int FEATURES_SIZE = 729;
 constexpr int DNN_BIASES_SIZE = 40;
 
 struct alignas(16) FixedAllocations {

chrome/browser/resource_coordinator/tab_ranker/tab_score_predictor_unittest.cc

@@ -135,7 +135,7 @@ TEST_F(TabScorePredictorTest, KnownScore) {
   window.tab_count = 27;
 
   // Pre-calculated score using the generated model outside of Chrome.
-  EXPECT_FLOAT_EQ(7.5816331, ScoreTab(tab, window, mru));
+  EXPECT_FLOAT_EQ(8.0287771, ScoreTab(tab, window, mru));
 }
 
 // Checks the score for a different example that we have calculated a known
@@ -164,7 +164,7 @@ TEST_F(TabScorePredictorTest, KnownScoreMissingOptionalFeatures) {
   window.tab_count = 127;
 
   // Pre-calculated score using the generated model outside of Chrome.
-  EXPECT_FLOAT_EQ(12.989228, ScoreTab(tab, window, mru));
+  EXPECT_FLOAT_EQ(10.577342, ScoreTab(tab, window, mru));
 }
 
 TEST_F(TabScorePredictorTest, InactiveDuration) {
@@ -195,12 +195,12 @@ TEST_F(TabScorePredictorTest, NumReactivationBefore) {
   float no_reactivations_score = ScoreTab(example);
 
   // A tab with reactivations is more likely to be reactivated than one without.
-  example.num_reactivations = 4;
+  example.num_reactivations = 10;
   float reactivations_score = ScoreTab(example);
   ASSERT_GT(reactivations_score, no_reactivations_score);
 
   // A tab with more reactivations is more likely to be reactivated.
-  example.num_reactivations = 10;
+  example.num_reactivations = 20;
   float more_reactivations_score = ScoreTab(example);
   ASSERT_GT(more_reactivations_score, reactivations_score);
 }
@@ -220,7 +220,7 @@ TEST_F(TabScorePredictorTest, PageTransitionTypes) {
 
 TEST_F(TabScorePredictorTest, SiteEngagementScore) {
   TabFeatures example = GetTabFeatures(kUnseenHost, true /*user_activity*/);
-  example.site_engagement_score = 0;
+  example.site_engagement_score.reset();
   float engagement_score_0 = ScoreTab(example);
 
   // A site with low engagement ranks higher than one with no engagement.
@@ -233,7 +233,7 @@ TEST_F(TabScorePredictorTest, SiteEngagementScore) {
   float engagement_score_medium = ScoreTab(example);
   ASSERT_GT(engagement_score_medium, engagement_score_low);
 
-  example.site_engagement_score = 100;
+  example.site_engagement_score = 80;
   float engagement_score_high = ScoreTab(example);
   ASSERT_GT(engagement_score_high, engagement_score_medium);
 }
@@ -249,12 +249,11 @@ TEST_F(TabScorePredictorTest, TopURLHigherScore) {
 }
 
 TEST_F(TabScorePredictorTest, TopURLLowerScore) {
-  // Expect Wikipedia tabs to be less likely to be reactivated.
-  // See also: https://xkcd.com/214/
+  // Expect www.google.com tabs to be less likely to be reactivated.
   TabFeatures unseen_example =
       GetTabFeatures(kUnseenHost, true /*user_activity*/);
   TabFeatures lower_example =
-      GetTabFeatures("en.wikipedia.org", true /*user_activity*/);
+      GetTabFeatures("www.google.com", true /*user_activity*/);
   ASSERT_LT(ScoreTab(lower_example), ScoreTab(unseen_example));
 }