Add UMA stats for tracking bookmark depth

chrome/browser/bookmarks/bookmark_stats.h

Index: chrome/browser/bookmarks/bookmark_stats.h
diff --git a/chrome/browser/bookmarks/bookmark_stats.h b/chrome/browser/bookmarks/bookmark_stats.h
index f7f8a822374aaa336371ee508a0e92450bfd1c51..af4d6ac0c25d0d058bac87ac001cfde9e2422818 100644
--- a/chrome/browser/bookmarks/bookmark_stats.h
+++ b/chrome/browser/bookmarks/bookmark_stats.h
@@ -5,6 +5,8 @@
 #ifndef CHROME_BROWSER_BOOKMARKS_BOOKMARK_STATS_H_
 #define CHROME_BROWSER_BOOKMARKS_BOOKMARK_STATS_H_
 
+class BookmarkNode;
+
 // This enum is used for the Bookmarks.EntryPoint histogram.
 enum BookmarkEntryPoint {
   BOOKMARK_ENTRY_POINT_ACCELERATOR,
@@ -38,7 +40,8 @@ enum BookmarkLaunchLocation {
 };
 
 // Records the launch of a bookmark for UMA purposes.
-void RecordBookmarkLaunch(BookmarkLaunchLocation location);
+void RecordBookmarkLaunch(const BookmarkNode* node,
+                          BookmarkLaunchLocation location);
 
 // Records the user opening a folder of bookmarks for UMA purposes.
 void RecordBookmarkFolderOpen(BookmarkLaunchLocation location);