[Zine] Add a metric to record number of visible sections on NTP.

chrome/browser/android/ntp/suggestions_event_reporter_bridge.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/android/ntp/suggestions_event_reporter_bridge.h"
 
 #include <jni.h>
 #include <vector>
 
 #include "base/android/jni_android.h"
@@ skipping 47 matching lines @@
                                       jlong visit_time_ms) {
   ntp_snippets::metrics::OnSuggestionTargetVisited(
       Category::FromIDValue(j_category_id),
       base::TimeDelta::FromMilliseconds(visit_time_ms));
 }
 
 static void OnPageShown(
     JNIEnv* env,
     const JavaParamRef<jclass>& caller,
     const JavaParamRef<jintArray>& jcategories,
-    const JavaParamRef<jintArray>& jsuggestions_per_category) {
+    const JavaParamRef<jintArray>& jsuggestions_per_category,
+    jint j_visible_categories_count) {
   std::vector<int> categories_int;
   JavaIntArrayToIntVector(env, jcategories, &categories_int);
   std::vector<int> suggestions_per_category_int;
   JavaIntArrayToIntVector(env, jsuggestions_per_category,
                           &suggestions_per_category_int);
   DCHECK_EQ(categories_int.size(), suggestions_per_category_int.size());
   std::vector<std::pair<Category, int>> suggestions_per_category;
   for (size_t i = 0; i < categories_int.size(); i++) {
     suggestions_per_category.push_back(
         std::make_pair(Category::FromIDValue(categories_int[i]),
                        suggestions_per_category_int[i]));
   }
-  ntp_snippets::metrics::OnPageShown(suggestions_per_category);
+  ntp_snippets::metrics::OnPageShown(suggestions_per_category,
+                                     j_visible_categories_count);
   GetUserClassifier()->OnEvent(UserClassifier::Metric::NTP_OPENED);
 }
 
 static void OnSuggestionShown(JNIEnv* env,
                               const JavaParamRef<jclass>& caller,
                               jint global_position,
                               jint j_category_id,
                               jint position_in_category,
                               jlong publish_timestamp_ms,
                               jfloat score,
@@ skipping 91 matching lines @@
   // TODO(fhorschig): Remove guard when https://crbug.com/678556 is resolved.
   if (!scheduler) {
     return;
   }
   scheduler->OnBrowserForegrounded();
 }
 
 bool RegisterSuggestionsEventReporterBridge(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }