[bookmarks] Avoid logging to bucket 0 for duplicates

This implementation is consistent with the documentation in
histograms.xml.

Change-Id: Ib85a290def5f09ef07f4a0740d4cc6f3ab9a7224
Bug: 1068378
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2517943
Auto-Submit: Mikel Astiz <mastiz@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Commit-Queue: Jesse Doherty <jwd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#823724}

components/bookmarks/browser/model_loader.cc

@@ -84,9 +84,12 @@ void LoadBookmarks(const base::FilePath& path,
   base::UmaHistogramCounts100000(
       "Bookmarks.Count.OnProfileLoad",
       base::saturated_cast<int>(stats.total_url_bookmark_count));
-  base::UmaHistogramCounts100000(
-      "Bookmarks.Count.OnProfileLoad.DuplicateUrl2",
-      base::saturated_cast<int>(stats.duplicate_url_bookmark_count));
+
+  if (stats.duplicate_url_bookmark_count != 0) {
+    base::UmaHistogramCounts100000(
+        "Bookmarks.Count.OnProfileLoad.DuplicateUrl2",
+        base::saturated_cast<int>(stats.duplicate_url_bookmark_count));
+  }
 }
 
 }  // namespace