Add Shortcuts database histogram.

chrome/browser/history/shortcuts_database.cc

Index: chrome/browser/history/shortcuts_database.cc
diff --git a/chrome/browser/history/shortcuts_database.cc b/chrome/browser/history/shortcuts_database.cc
index f739073d894c22686a06c2294592a8eadec9ae37..dfce9383ee07f4fbf210498b98e0ca535b05481a 100644
--- a/chrome/browser/history/shortcuts_database.cc
+++ b/chrome/browser/history/shortcuts_database.cc
@@ -57,6 +57,8 @@ ShortcutsDatabase::ShortcutsDatabase(Profile* profile) {
 }
 
 bool ShortcutsDatabase::Init() {
+  db_.set_histogram_tag("Shortcuts");
+
   // Set the database page size to something a little larger to give us
   // better performance (we're typically seek rather than bandwidth limited).
   // This only has an effect before any tables have been created, otherwise