Do not trigger layout in PasswordAutofillAgent::DidFinishDocumentLoad

components/autofill/content/renderer/form_autofill_util.h

 // 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.
 
 #ifndef COMPONENTS_AUTOFILL_CONTENT_RENDERER_FORM_AUTOFILL_UTIL_H_
 #define COMPONENTS_AUTOFILL_CONTENT_RENDERER_FORM_AUTOFILL_UTIL_H_
 
 #include <stddef.h>
 
 #include <vector>
 
+#include "base/macros.h"
 #include "base/strings/string16.h"
 #include "components/autofill/core/common/autofill_constants.h"
 #include "components/autofill/core/common/password_form_field_prediction_map.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
 #include "third_party/WebKit/public/web/WebElementCollection.h"
 #include "ui/gfx/geometry/rect_f.h"
 
 class GURL;
 
 namespace blink {
@@ skipping 28 matching lines @@
 };
 
 // The maximum number of form fields we are willing to parse, due to
 // computational costs.  Several examples of forms with lots of fields that are
 // not relevant to Autofill: (1) the Netflix queue; (2) the Amazon wishlist;
 // (3) router configuration pages; and (4) other configuration pages, e.g. for
 // Google code project settings.
 // Copied to components/autofill/ios/browser/resources/autofill_controller.js.
 extern const size_t kMaxParseableFields;
 
+// Create an instance of ScopedLayoutPreventer to stop form_util code from
+// triggering layout as a side-effect. For example, when creating a
+// FormFieldData, a call to WebNode::isFocusable is normally made, which may
+// trigger a layout computation. When an instance of ScopedLayoutPreventer is
+// alive, that call will not be made. On destruction, this class allows
+// layout-triggering calls again. It is not thread safe and multiple instances
+// should not be created at the same time in the same process.
+class ScopedLayoutPreventer {
+ public:
+  ScopedLayoutPreventer();
+  ~ScopedLayoutPreventer();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ScopedLayoutPreventer);
+};
+
 // Extract FormData from the form element and return whether the operation was
 // successful.
 bool ExtractFormData(const blink::WebFormElement& form_element, FormData* data);
 
 // Helper function to check if there exist any form on |frame| where its action
 // equals |action|. Returns true if so. For forms with empty or unspecified
 // actions, all form data are used for comparison. Form data comparison is
 // disabled on Mac and Android because the update prompt isn't implemented.
 // It may cause many false password updates.
 // TODO(kolos) Turn on all data comparing when the update prompt will be
@@ skipping 167 matching lines @@
 // |input_element|. Note that |user_input| cannot be easily derived from
 // |input_element| by calling value(), because of http://crbug.com/507714.
 void PreviewSuggestion(const base::string16& suggestion,
                        const base::string16& user_input,
                        blink::WebFormControlElement* input_element);
 
 }  // namespace form_util
 }  // namespace autofill
 
 #endif  // COMPONENTS_AUTOFILL_CONTENT_RENDERER_FORM_AUTOFILL_UTIL_H_