.

chrome/renderer/resources/extensions/omnibox_custom_bindings.js

Index: chrome/renderer/resources/extensions/omnibox_custom_bindings.js
diff --git a/chrome/renderer/resources/extensions/omnibox_custom_bindings.js b/chrome/renderer/resources/extensions/omnibox_custom_bindings.js
index fa0ced3aa34515132f9f4c72a0a07b71fe0ea065..e41d11447afd312cca60a9712941511db85ecf88 100644
--- a/chrome/renderer/resources/extensions/omnibox_custom_bindings.js
+++ b/chrome/renderer/resources/extensions/omnibox_custom_bindings.js
@@ -84,6 +84,16 @@ function parseOmniboxDescription(input) {
 binding.registerCustomHook(function(bindingsAPI) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
+  apiFunctions.setUpdateArgumentsPreValidate('setDefaultSuggestions',
+                                             function(suggestResult) {
+    if (suggestResult.content != undefined) {  // null, etc.
+      throw new Error(
+          'setDefaultSuggestions cannot contain the "content" field');
+    }
+    suggestResult.content = '';
+    return [suggestResult];
+  });
+
   apiFunctions.setHandleRequest('setDefaultSuggestion', function(details) {
     var parseResult = parseOmniboxDescription(details.description);
     sendRequest(this.name, [parseResult], this.definition.parameters);