new URL('') should throw TypeError

components/autofill/content/renderer/form_autofill_util.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/content/renderer/form_autofill_util.h"
 
 #include <map>
 #include <set>
 
 #include "base/command_line.h"
@@ skipping 1103 matching lines @@
 bool IsFormVisible(blink::WebFrame* frame,
                    const GURL& canonical_action,
                    const GURL& canonical_origin,
                    const FormData& form_data,
                    const FormsPredictionsMap& form_predictions) {
   const GURL frame_url = GURL(frame->document().url().string().utf8());
   blink::WebVector<blink::WebFormElement> forms;
   frame->document().forms(forms);
 
 #if !defined(OS_MACOSX) && !defined(OS_ANDROID)
-  const bool action_is_empty = canonical_action == canonical_origin;
+  // Omitting the action attribute would result in |canonical_origin| for
+  // hierarchical schemes like http:, and in an empty URL for non-hierarchical
+  // schemes like about: or data: etc.
+  const bool action_is_empty = canonical_action.is_empty()
+                               || canonical_action == canonical_origin;
 #endif
 
   // Since empty or unspecified action fields are automatically set to page URL,
   // action field for forms cannot be used for comparing (all forms with
   // empty/unspecified actions have the same value). If an action field is set
   // to the page URL, this method checks ALL fields of the form instead (using
   // FormData.SameFormAs). This is also true if the action was set to the page
   // URL on purpose.
   for (size_t i = 0; i < forms.size(); ++i) {
     const blink::WebFormElement& form = forms[i];
     if (!IsWebNodeVisible(form))
       continue;
 
     GURL iter_canonical_action = GetCanonicalActionForForm(form);
 #if !defined(OS_MACOSX) && !defined(OS_ANDROID)
-    bool form_action_is_empty = iter_canonical_action == frame_url;
+    bool form_action_is_empty = iter_canonical_action.is_empty()
+                                || iter_canonical_action == frame_url;
 
     if (action_is_empty != form_action_is_empty)
       continue;
 
     if (action_is_empty) {  // Both actions are empty, compare all fields.
       FormData extracted_form_data;
       WebFormElementToFormData(form, blink::WebFormControlElement(),
                                EXTRACT_NONE, &extracted_form_data, nullptr);
       if (form_data.SameFormAs(extracted_form_data)) {
         return true;  // Form still exists.
@@ skipping 492 matching lines @@
     // Zero selection start is for password manager, which can show usernames
     // that do not begin with the user input value.
     selection_start = (offset == base::string16::npos) ? 0 : offset;
   }
 
   input_element->setSelectionRange(selection_start, suggestion.length());
 }
 
 }  // namespace form_util
 }  // namespace autofill