Do not trigger layout in PasswordAutofillAgent::DidFinishDocumentLoad

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 53 matching lines @@
   // Filters non-focusable elements with the exception of select elements, which
   // are sometimes made non-focusable because they are present for accessibility
   // while a prettier, non-<select> dropdown is shown. We still want to autofill
   // the non-focusable <select>.
   FILTER_NON_FOCUSABLE_ELEMENTS    = 1 << 2,
   FILTER_ALL_NON_EDITABLE_ELEMENTS = FILTER_DISABLED_ELEMENTS |
                                      FILTER_READONLY_ELEMENTS |
                                      FILTER_NON_FOCUSABLE_ELEMENTS,
 };
 
+// If true, operations causing layout computation should be avoided. Set by
+// ScopedLayoutPreventer.
+bool g_prevent_layout = false;
+
 void TruncateString(base::string16* str, size_t max_length) {
   if (str->length() > max_length)
     str->resize(max_length);
 }
 
 bool IsOptionElement(const WebElement& element) {
   CR_DEFINE_STATIC_LOCAL(WebString, kOption, ("option"));
   return element.hasHTMLTagName(kOption);
 }
 
@@ skipping 731 matching lines @@
         // input field's "value" or "placeholder" attribute, is skipped.
         (IsAutofillableInputElement(input_element) ||
          IsTextAreaElement(*element)) &&
         !element->value().isEmpty() &&
         (!element->hasAttribute(kValue) ||
          element->getAttribute(kValue) != element->value()) &&
         (!element->hasAttribute(kPlaceholder) ||
          element->getAttribute(kPlaceholder) != element->value()))
       continue;
 
+    DCHECK(!g_prevent_layout || !(filters & FILTER_NON_FOCUSABLE_ELEMENTS))
+        << "The callsite of this code wanted to both prevent layout and check "
+           "isFocusable. Pick one.";
     if (((filters & FILTER_DISABLED_ELEMENTS) && !element->isEnabled()) ||
         ((filters & FILTER_READONLY_ELEMENTS) && element->isReadOnly()) ||
         // See description for FILTER_NON_FOCUSABLE_ELEMENTS.
         ((filters & FILTER_NON_FOCUSABLE_ELEMENTS) && !element->isFocusable() &&
          !IsSelectElement(*element)))
       continue;
 
     callback(data.fields[i], is_initiating_element, element);
   }
 }
@@ skipping 330 matching lines @@
   GURL::Replacements rep;
   rep.ClearUsername();
   rep.ClearPassword();
   rep.ClearQuery();
   rep.ClearRef();
   return gurl.ReplaceComponents(rep);
 }
 
 }  // namespace
 
+ScopedLayoutPreventer::ScopedLayoutPreventer() {
+  DCHECK(!g_prevent_layout) << "Is any other instance of ScopedLayoutPreventer "
+                               "alive in the same process?";
+  g_prevent_layout = true;
+}
+
+ScopedLayoutPreventer::~ScopedLayoutPreventer() {
+  DCHECK(g_prevent_layout) << "Is any other instance of ScopedLayoutPreventer "
+                              "alive in the same process?";
+  g_prevent_layout = false;
+}
+
 bool ExtractFormData(const WebFormElement& form_element, FormData* data) {
   return WebFormElementToFormData(
       form_element, WebFormControlElement(),
       static_cast<form_util::ExtractMask>(form_util::EXTRACT_VALUE |
                                           form_util::EXTRACT_OPTION_TEXT |
                                           form_util::EXTRACT_OPTIONS),
       data, NULL);
 }
 
 bool IsFormVisible(blink::WebFrame* frame,
@@ skipping 182 matching lines @@
   field->placeholder = element.getAttribute(kPlaceholder);
 
   if (!IsAutofillableElement(element))
     return;
 
   const WebInputElement* input_element = toWebInputElement(&element);
   if (IsAutofillableInputElement(input_element) ||
       IsTextAreaElement(element) ||
       IsSelectElement(element)) {
     field->is_autofilled = element.isAutofilled();
-    field->is_focusable = element.isFocusable();
+    if (!g_prevent_layout)
+      field->is_focusable = element.isFocusable();
     field->should_autocomplete = element.autoComplete();
     field->text_direction = element.directionForFormData() ==
         "rtl" ? base::i18n::RIGHT_TO_LEFT : base::i18n::LEFT_TO_RIGHT;
   }
 
   if (IsAutofillableInputElement(input_element)) {
     if (IsTextInput(input_element))
       field->max_length = input_element->maxLength();
 
     field->is_checkable = IsCheckableElement(input_element);
@@ skipping 378 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