Fix histogram ExploreSites.ClickedNTPCategoryIndex bucket count.

Bug: 896481
Change-Id: I6e7d05e5673971d2b132e75dcaf1dfe7a858357a
Reviewed-on: https://chromium-review.googlesource.com/c/1287290Reviewed-by: Justin DeWitt <dewittj@chromium.org>
Commit-Queue: Dmitry Titov <dimich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#600588}

chrome/android/java/src/org/chromium/chrome/browser/explore_sites/ExploreSitesSection.java

@@ -37,9 +37,10 @@ public class ExploreSitesSection {
     private static final String TAG = "ExploreSitesSection";
     private static final int MAX_CATEGORIES = 3;
     // This is a number of UMA histogram buckets that should be an upper bound
-    // of MAX_CATEGORIES over time, plus 1 for "More" button. If MAX_CATEGORIES
-    // changes, this value should be updated only upwards.
-    private static final int MAX_CATEGORIES_HISTOGRAM_BUCKETS = 4;
+    // of MAX_CATEGORIES over time, plus 1 for "More" button, and plus 1 for
+    // overflow bucket. If MAX_CATEGORIES changes, this value should be updated
+    // only upwards.
+    private static final int MAX_CATEGORIES_HISTOGRAM_BUCKETS = 5;
 
     @TileStyle
     private int mStyle;
@@ -194,7 +195,7 @@ public class ExploreSitesSection {
 
     private void onClicked(int tileIndex, ExploreSitesCategory category, View v) {
         RecordHistogram.recordLinearCountHistogram("ExploreSites.ClickedNTPCategoryIndex",
-                tileIndex, 0, MAX_CATEGORIES_HISTOGRAM_BUCKETS, MAX_CATEGORIES_HISTOGRAM_BUCKETS);
+                tileIndex, 0, MAX_CATEGORIES, MAX_CATEGORIES_HISTOGRAM_BUCKETS);
         mNavigationDelegate.openUrl(WindowOpenDisposition.CURRENT_TAB,
                 new LoadUrlParams(category.getUrl(), PageTransition.AUTO_BOOKMARK));
     }