options: fix "Import" button for idle options pages.

chrome/browser/resources/options/import_data_overlay.js

Index: chrome/browser/resources/options/import_data_overlay.js
diff --git a/chrome/browser/resources/options/import_data_overlay.js b/chrome/browser/resources/options/import_data_overlay.js
index 600c9fa89b86771285d54a8b8d55779bd1d8caa0..a5907f00874e065a6daac99948e892d9a6ed4248 100644
--- a/chrome/browser/resources/options/import_data_overlay.js
+++ b/chrome/browser/resources/options/import_data_overlay.js
@@ -32,8 +32,10 @@ cr.define('options', function() {
       var checkboxes =
           document.querySelectorAll('#import-checkboxes input[type=checkbox]');
       for (var i = 0; i < checkboxes.length; i++) {
-        checkboxes[i].onchange = function() {
+        checkboxes[i].customPrefChangeHandler = function(e) {
+          options.PrefCheckbox.prototype.defaultPrefChangeHandler.call(this, e);
           self.validateCommitButton_();
+          return true;
         };
       }