Add Bookmarks.BookmarksInFolder histogram to bookmark manager.

chrome/browser/resources/bookmark_manager/js/bmm/bookmark_list.js

Index: chrome/browser/resources/bookmark_manager/js/bmm/bookmark_list.js
diff --git a/chrome/browser/resources/bookmark_manager/js/bmm/bookmark_list.js b/chrome/browser/resources/bookmark_manager/js/bmm/bookmark_list.js
index 4914b68e8c26e355cd7f83febb7473aebaccd6e4..089b77a70448aa673f88856568f61d8133d988f2 100644
--- a/chrome/browser/resources/bookmark_manager/js/bmm/bookmark_list.js
+++ b/chrome/browser/resources/bookmark_manager/js/bmm/bookmark_list.js
@@ -149,6 +149,15 @@ cr.define('bmm', function() {
 
       this.fixWidth_();
       cr.dispatchSimpleEvent(this, 'load');
+
+      // Use the same histogram configuration as UMA_HISTOGRAM_COUNTS_1000().
+      chrome.metricsPrivate.recordValue({
+        'metricName': 'Bookmarks.BookmarksInFolder',
+        'type': chrome.metricsPrivate.MetricTypeType.HISTOGRAM_LOG,
+        'min': 1,
+        'max': 1000,
+        'buckets': 50
+      }, this.dataModel.length);
     },
 
     /**