Add search hint bubbles to Print Preview advanced options controls.

chrome/browser/resources/print_preview/common/search_box.js

Index: chrome/browser/resources/print_preview/common/search_box.js
diff --git a/chrome/browser/resources/print_preview/common/search_box.js b/chrome/browser/resources/print_preview/common/search_box.js
index 4291dbf9482d3e1fb4cba6609577a78ce32927f7..d7c1abc4722c707116040afb455d143c4b02ad7f 100644
--- a/chrome/browser/resources/print_preview/common/search_box.js
+++ b/chrome/browser/resources/print_preview/common/search_box.js
@@ -99,9 +99,13 @@ cr.define('print_preview', function() {
       var searchEvent = new Event(SearchBox.EventType.SEARCH);
       var query = this.getQuery_();
       searchEvent.query = query;
-      // Generate regexp-safe query by escaping metacharacters.
-      var safeQuery = query.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
-      searchEvent.queryRegExp = new RegExp('(' + safeQuery + ')', 'ig');
+      if (query) {
+        // Generate regexp-safe query by escaping metacharacters.
+        var safeQuery = query.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, '\\$&');
+        searchEvent.queryRegExp = new RegExp('(' + safeQuery + ')', 'ig');
+      } else {
+        searchEvent.queryRegExp = null;
+      }
       this.dispatchEvent(searchEvent);
     },