[iOS] Upstream autofill component code

components/autofill/ios/browser/resources/autofill_controller.js

Index: components/autofill/ios/browser/resources/autofill_controller.js
diff --git a/components/autofill/ios/browser/resources/autofill_controller.js b/components/autofill/ios/browser/resources/autofill_controller.js
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+// 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.
+
+// Installs Autofill management functions on the |__gCrWeb| object.
+//
+// It scans the DOM, extracting and storing forms and returns a JSON string
+// representing an array of objects, each of which represents an Autofill form
+// with information about a form to be filled and/or submitted and it can be
+// translated to struct FormData
+// (chromium/src/components/autofill/common/form_data.h) for further processing.
+
+/**
+ * Namespace for this file. It depends on |__gCrWeb| having already been
+ * injected.
+ */
+__gCrWeb['autofill'] = {};
+
+/**
+ * The maximum length allowed for form data.
+ *
+ * This variable is from
+ * chromium/src/components/autofill/renderer/form_autofill_util.cc
+ */
+__gCrWeb.autofill.MAX_DATA_LENGTH = 1024;
+
+/**
+ * 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.
+ *
+ * This variable is from
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.MAX_PARSEABE_FIELDS = 100;
+
+/**
+ * A bit field mask for form or form element requirements for requirement
+ * none.
+ *
+ * This variable is from enum RequirementsMask in
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.REQUIREMENTS_MASK_NONE = 0;
+
+/**
+ * A bit field mask for form or form element requirements for requirement
+ * autocomplete != off.
+ *
+ * This variable is from enum RequirementsMask in
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.REQUIREMENTS_MASK_REQUIRE_AUTOCOMPLETE = 1;
+
+/**
+ * A bit field mask to extract data from WebFormControlElement for
+ * extracting none value.
+ *
+ * This variable is from enum ExtractMask in
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.EXTRACT_MASK_NONE = 0;
+
+/**
+ * A bit field mask to extract data from WebFormControlElement for
+ * extracting value from WebFormControlElement.
+ *
+ * This variable is from enum ExtractMask in
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.EXTRACT_MASK_VALUE = 1 << 0;
+
+/**
+ * A bit field mask to extract data from WebFormControlElement for
+ * extracting option text from WebFormSelectElement. Only valid when
+ * EXTRACT_MASK_VALUE is set. This is used for form submission where human
+ * readable value is captured.
+ *
+ * This variable is from enum ExtractMask in
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.EXTRACT_MASK_OPTION_TEXT = 1 << 1;
+
+/**
+ * A bit field mask to extract data from WebFormControlElement for
+ * extracting options from WebFormControlElement.
+ *
+ * This variable is from enum ExtractMask in
+ * chromium/src/components/autofill/renderer/form_autofill_util.h
+ */
+__gCrWeb.autofill.EXTRACT_MASK_OPTIONS = 1 << 2;
+
+/**
+ * The last element that was autofilled.
+ */
+__gCrWeb.autofill.lastAutoFilledElement = null;
+
+/**
+ * Scans DOM and returns a JSON string representation of forms and form
+ * extraction results.
+ * @param {int} requiredFields The minimum number of fields forms must have to
+ *     be extracted.
+ * @param {int} requirements The requirements mask for forms, e.g. autocomplete
+ *     attribute state.
+ * @return {string} A JSON encoded object with object['forms'] containing the
+ *     forms data and object['has_more_forms'] indicating if there are more
+ *     forms to extract.
+ */
+__gCrWeb.autofill['extractForms'] = function(requiredFields, requirements) {
+  var forms = [];
+  // Protect against custom implementation of Array.toJSON in host pages.
+  forms.toJSON = null;
+  // TODO(chenyu): check if any preparation is needed for information such as
+  // user_submitted or the one added in core.js is sufficient.
+  var hasMoreForms = __gCrWeb.autofill.extractFormsAndFormElements(
+      window,
+      requiredFields,
+      requirements,
+      forms);
+  var results = new __gCrWeb.common.JSONSafeObject;
+  results['has_more_forms'] = hasMoreForms;
+  results['forms'] = forms;
+  return __gCrWeb.stringify(results);
+};
+
+/**
+ * Fills data into the active form field.
+ *
+ * @param {Object} data The data to fill in.
+ */
+__gCrWeb.autofill['fillActiveFormField'] = function(data) {
+  var activeElement = document.activeElement;
+  if (data['name'] !== __gCrWeb['common'].nameForAutofill(activeElement)) {
+    return;
+  }
+  __gCrWeb.autofill.lastAutoFilledElement = activeElement;
+  __gCrWeb.autofill.fillFormField(data, activeElement);
+};
+
+/**
+ * Fills a number of fields in the same named form.
+ *
+ * @param {Object} data The data to fill in.
+ */
+__gCrWeb.autofill['fillForm'] = function(data) {
+  var form = __gCrWeb.common.getFormElementFromIdentifier(data.formName);
+  var controlElements = __gCrWeb.common.getFormControlElements(form);
+  for (var i = 0; i < controlElements.length; ++i) {
+    var element = controlElements[i];
+    if (!__gCrWeb.autofill.isAutofillableElement(element)) {
+      continue;
+    }
+    var value = data.fields[__gCrWeb['common'].nameForAutofill(element)];
+    if (value) {
+      element.value = value;
+    }
+  }
+};
+
+/**
+ * Dispatch an autocomplete event to the named form.
+ *
+ * @param {String} name Identifier for form element (from getFormIdentifier).
+ */
+__gCrWeb.autofill['dispatchAutocompleteEvent'] = function(name) {
+  var formElement = __gCrWeb.common.getFormElementFromIdentifier(name);
+  var event = new CustomEvent('autocomplete', {});
+  formElement.dispatchEvent(event);
+};
+
+/**
+ * Dispatch an autocomplete error event to the named form.
+ *
+ * @param {String} name Identifier for form element (from getFormIdentifier).
+ * @param {String} reason Reason to supply in event.reason; one of 'cancel',
+ *     'invalid' or 'disabled'; see requestAutocomplete spec.
+ */
+__gCrWeb.autofill['dispatchAutocompleteErrorEvent'] = function(name, reason) {
+  var formElement = __gCrWeb.common.getFormElementFromIdentifier(name);
+  var event = new CustomEvent('autocompleteerror', {});
+  event.reason = reason;
+  formElement.dispatchEvent(event);
+};
+
+/**
+ * Dispatch an autocomplete error event to the named form.
+ *
+ * @param {String} name Identifier for form element (from getFormIdentifier).
+ * @param {String} reason Reason to supply in event.reason; one of 'cancel',
+ *     'invalid' or 'disabled'; see requestAutocomplete spec.
+ */
+__gCrWeb.autofill['dispatchAutocompleteErrorEvent'] = function(name, reason) {
+  var formElement = __gCrWeb.common.getFormElementFromIdentifier(name);
+  var event = new CustomEvent('autocompleteerror', {});
+  event.reason = reason;
+  formElement.dispatchEvent(event);
+};
+
+/**
+ * Scans the DOM in |frame| extracting and storing forms. Fills |forms| with
+ * extracted forms. Returns true if there are unextracted forms due to
+ * |minimumRequiredFields| limit, else false.
+ *
+ * This method is based on the logic in method
+ *
+ *     bool FormCache::ExtractFormsAndFormElements(
+ *         const WebFrame& frame,
+ *         size_t minimum_required_fields,
+ *         std::vector<FormData>* forms,
+ *         std::vector<WebFormElement>* web_form_elements)
+ *
+ * in chromium/src/components/autofill/renderer/form_cache.cc.
+ *
+ * The difference is in this implementation, no form elements are returned in
+ * |web_form_elements|, and cache is not considered. Initial values of select
+ * and checkable elements are not recorded at the momemt.
+ *
+ * @param {Object} frame A window or a frame containing forms from which the
+ *     data will be extracted.
+ * @param {int} minimumRequiredFields The minimum number of fields a form should
+ *     contain for autofill.
+ * @param {int} requirements The requirements mask for forms, e.g. autocomplete
+ *     attribute state.
+ * @param {Object} forms Forms that will be filled in data of forms in frame.
+ * @return {boolean} Whether there are unextracted forms due to
+ *     |minimumRequiredFields| limit.
+ */
+__gCrWeb.autofill.extractFormsAndFormElements = function(
+    frame, minimumRequiredFields, requirements, forms) {
+  if (!frame) {
+    return false;
+  }
+  var doc = frame.document;
+  if (!doc) {
+    return false;
+  }
+
+  var webForms = doc.forms;
+
+  var numFieldsSeen = 0;
+  var hasSkippedForms = false;
+  for (var formIndex = 0; formIndex < webForms.length; ++formIndex) {
+    var formElement = webForms[formIndex];
+    var controlElements = [];
+    __gCrWeb.autofill.extractAutofillableElements(
+        formElement, requirements, controlElements);
+    var numEditableElements = 0;
+    for (var elementIndex = 0; elementIndex < controlElements.length;
+         ++elementIndex) {
+      var element = controlElements[elementIndex];
+      if (!__gCrWeb.autofill.isCheckableElement(element)) {
+        ++numEditableElements;
+      }
+    }
+
+    // To avoid overly expensive computation, we impose a minimum number of
+    // allowable fields.  The corresponding maximum number of allowable
+    // fields is imposed by webFormElementToFormData().
+    if (numEditableElements < minimumRequiredFields) {
+      hasSkippedForms = true;
+      continue;
+    }
+
+    var extractMask = __gCrWeb.autofill.EXTRACT_MASK_VALUE |
+        __gCrWeb.autofill.EXTRACT_MASK_OPTIONS;
+    var form = new __gCrWeb['common'].JSONSafeObject;
+    if (!__gCrWeb.autofill.webFormElementToFormData(
+        frame, formElement, null, requirements, extractMask, form)) {
+      continue;
+    }
+    numFieldsSeen += form['fields'].length;
+    if (numFieldsSeen > __gCrWeb.autofill.MAX_PARSEABE_FIELDS) {
+      break;
+    }
+
+    if (form.fields.length >= minimumRequiredFields) {
+      forms.push(form);
+    } else {
+      hasSkippedForms = true;
+    }
+  }
+
+  // Recursively invoke for all frames/iframes.
+  var frames = frame.frames;
+  for (var i = 0; i < frames.length; i++) {
+    var hasSkippedInframe = __gCrWeb.autofill.extractFormsAndFormElements(
+            frames[i], minimumRequiredFields, requirements, forms);
+    hasSkippedForms = hasSkippedForms || hasSkippedInframe;
+  }
+  return hasSkippedForms;
+};
+
+/**
+ * Fills |form| with the form data object corresponding to the |formElement|.
+ * If |field| is non-NULL, also fills |field| with the FormField object
+ * corresponding to the |formControlElement|.
+ * |extract_mask| controls what data is extracted.
+ * Returns true if |form| is filled out; it's possible that the |formElement|
+ * won't meet the |requirements|.  Also returns false if there are no fields or
+ * too many fields in the |form|.
+ *
+ * It is based on the logic in
+ *     bool WebFormElementToFormData(
+ *         const blink::WebFormElement& form_element,
+ *         const blink::WebFormControlElement& form_control_element,
+ *         RequirementsMask requirements,
+ *         ExtractMask extract_mask,
+ *         FormData* form,
+ *         FormFieldData* field)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc
+ *
+ * @param {Element} frame The frame where the formElement is in.
+ * @param {Element} formElement The form element that will be processed.
+ * @param {Element} formControlElement A control element in formElment, the
+ *     FormField of which will be returned in field.
+ * @param {int} requirements The requirement on formElement autocompletion.
+ * @param {int} extractMask Mask controls what data is extracted from
+ *     formElement.
+ * @param {Object} form Form to fill in the FormData information of formElement.
+ * @param {Object} field Field to fill in the form field information of
+ *     formControlElement.
+ * @return {boolean} Whether there are fields and not too many fields in the
+ *     form.
+ */
+__gCrWeb.autofill.webFormElementToFormData = function(
+    frame, formElement, formControlElement, requirements, extractMask, form,
+    field) {
+  if (!frame) {
+    return false;
+  }
+
+  if ((requirements &
+           __gCrWeb.autofill.REQUIREMENTS_MASK_REQUIRE_AUTOCOMPLETE) &&
+         !__gCrWeb['common'].autoComplete(formElement)) {
+    return false;
+  }
+
+  form['name'] = __gCrWeb.common.getFormIdentifier(formElement);
+  var method = formElement.getAttribute('method');
+  if (method) {
+    form['method'] = method;
+  }
+  form['origin'] = __gCrWeb.common.removeQueryAndReferenceFromURL(
+      frame.location.href);
+  form['action'] = __gCrWeb.common.absoluteURL(
+      frame.document,
+      formElement.getAttribute('action'));
+  // TODO(chenyu): fill form['userSubmitted'] (Issue 231264).
+
+  // Note different from form_autofill_utill.cc version of this method, which
+  // computes |form.action| using document.completeURL(form_element.action())
+  // and falls back to formElement.action() if the computed action is invalid,
+  // here the action returned by |__gCrWeb.common.absoluteURL| is always
+  // valid, which is computed by creating a <a> element, and we don't check if
+  // the action is valid.
+
+  // A map from a FormFieldData's name to the FormFieldData itself.
+  var nameMap = {};
+
+  // The extracted FormFields.
+  var formFields = [];
+
+  var controlElements = __gCrWeb['common'].getFormControlElements(formElement);
+
+  // A vector of bools that indicate whether each element in |controlElements|
+  // meets the requirements and thus will be in the resulting |form|.
+  var fieldsExtracted = [];
+
+  for (var i = 0; i < controlElements.length; ++i) {
+    fieldsExtracted[i] = false;
+
+    var controlElement = controlElements[i];
+    if (!__gCrWeb.autofill.isAutofillableElement(controlElement)) {
+      continue;
+    }
+
+    if (requirements &
+            __gCrWeb.autofill.REQUIREMENTS_MASK_REQUIRE_AUTOCOMPLETE &&
+        __gCrWeb.autofill.isAutofillableInputElement(controlElement) &&
+        !__gCrWeb.autofill.satisfiesRequireAutocomplete(
+            controlElement, false)) {
+      continue;
+    }
+
+    // Create a new FormFieldData, fill it out and map it to the field's name.
+    var formField = new __gCrWeb['common'].JSONSafeObject;
+    __gCrWeb.autofill.webFormControlElementToFormField(
+        controlElement, extractMask, formField);
+    formFields.push(formField);
+    nameMap[formField['name']] = formField;
+    fieldsExtracted[i] = true;
+
+    // To avoid overly expensive computation, we impose a maximum number of
+    // allowable fields.
+    if (formFields.length > __gCrWeb.autofill.MAX_PARSEABE_FIELDS) {
+      return false;
+    }
+  }
+
+  // If we failed to extract any fields, give up.
+  if (formFields.length === 0) {
+    return false;
+  }
+
+  // Loop through the label elements inside the form element. For each label
+  // element, get the corresponding form control element, use the form control
+  // element's name as a key into the <name, FormFieldData> nameMap to find the
+  // previously created FormFieldData and set the FormFieldData's label.
+  var labels = formElement.getElementsByTagName('label');
+  for (var index = 0; index < labels.length; ++index) {
+    var label = labels[index];
+    if (!label.control && !label.htmlFor) {
+      continue;
+    }
+    var fieldElement = label.control;
+    var elementName;
+    if (!fieldElement) {
+      // Sometimes site authors will incorrectly specify the corresponding
+      // field element's name rather than its id, so we compensate here.
+      elementName = label.htmlFor;
+    } else if (fieldElement.form != formElement ||
+                   fieldElement.type === 'hidden') {
+      continue;
+    } else {
+      elementName = __gCrWeb['common'].nameForAutofill(fieldElement);
+    }
+
+    var fieldElementData = nameMap[elementName];
+    if (fieldElementData) {
+      if (!fieldElementData['label']) {
+        fieldElementData['label'] = '';
+      }
+      var labelText = __gCrWeb.autofill.findChildText(label);
+      // Concatenate labels because some sites might have multiple label
+      // candidates.
+      if (fieldElementData['label'].length > 0 &&
+          labelText.length > 0) {
+        fieldElementData['label'] += ' ';
+      }
+      fieldElementData['label'] += labelText;
+    }
+  }
+
+  // Loop through the form control elements, extracting the label text from
+  // the DOM.  We use the |fieldsExtracted| vector to make sure we assign the
+  // extracted label to the correct field, as it's possible |form_fields| will
+  // not contain all of the elements in |control_elements|.
+  for (var i = 0, fieldIdx = 0;
+       i < controlElements.length && fieldIdx < formFields.length; ++i) {
+    // This field didn't meet the requirements, so don't try to find a label
+    // for it.
+    if (!fieldsExtracted[i])
+      continue;
+
+    var controlElement = controlElements[i];
+    var fieldLabel = formFields[fieldIdx]['label'];
+    if (!fieldLabel || fieldLabel.length === 0) {
+      formFields[fieldIdx]['label'] =
+          __gCrWeb.autofill.inferLabelForElement(controlElement);
+    }
+    if (controlElement === formControlElement)
+      field = formField;
+    ++fieldIdx;
+  }
+
+  form['fields'] = formFields;
+  // Protect against custom implementation of Array.toJSON in host pages.
+  form['fields'].toJSON = null;
+  return true;
+};
+
+/**
+ * Returns is the tag of an |element| is tag.
+ *
+ * It is based on the logic in
+ *     bool HasTagName(const WebNode& node, const blink::WebString& tag)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} node Node to examine.
+ * @param {string} tag Tag name.
+ * @return {boolean} Whether the tag of node is tag.
+ */
+__gCrWeb.autofill.hasTagName = function(node, tag) {
+  return node.nodeType === document.ELEMENT_NODE &&
+         node.tagName === tag.toUpperCase();
+};
+
+/**
+ * Checks if an element is autofillable.
+ *
+ * It is based on the logic in
+ *     bool IsAutofillableElement(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {boolean} Whether element is one of the element types that can be
+ *     autofilled.
+ */
+__gCrWeb.autofill.isAutofillableElement = function(element) {
+  return __gCrWeb.autofill.isAutofillableInputElement(element) ||
+         __gCrWeb.autofill.isSelectElement(element) ||
+         __gCrWeb.autofill.isTextAreaElement(element);
+};
+
+/**
+ * Check whether the given field satisfies the
+ * __gCrWeb.autofill.REQUIREMENTS_MASK_REQUIRE_AUTOCOMPLETE requirement. When
+ * Autocheckout is enabled, all fields are considered to satisfy this
+ * requirement.
+ *
+ * It is based on the logic in
+ *     bool SatisfiesRequireAutocomplete(const WebInputElement& input_element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element The element to be examined.
+ * @param {boolean} isExperimentalFormFillingEnabled Boolean from
+ *     switches::kEnableExperimentalFormFilling.
+ * @return {boolean} Whether the inputElement satisfies the requirement.
+ */
+__gCrWeb.autofill.satisfiesRequireAutocomplete = function(
+    element, isExperimentalFormFillingEnabled) {
+  return __gCrWeb.common.autoComplete(element) ||
+         isExperimentalFormFillingEnabled;
+};
+
+/**
+ * Trims whitespace from the start of the input string.
+ * Simplified version of string_util::TrimWhitespace.
+ * @param {string} input String to trim.
+ * @return {string} The |input| string without leading whitespace.
+ */
+__gCrWeb.autofill.trimWhitespaceLeading = function(input) {
+  return input.replace(/^\s+/gm, '');
+};
+
+/**
+ * Trims whitespace from the end of the input string.
+ * Simplified version of string_util::TrimWhitespace.
+ * @param {string} input String to trim.
+ * @return {string} The |input| string without trailing whitespace.
+ */
+__gCrWeb.autofill.trimWhitespaceTrailing = function(input) {
+  return input.replace(/\s+$/gm, '');
+};
+
+/**
+ * Appends |suffix| to |prefix| so that any intermediary whitespace is collapsed
+ * to a single space.  If |force_whitespace| is true, then the resulting string
+ * is guaranteed to have a space between |prefix| and |suffix|.  Otherwise, the
+ * result includes a space only if |prefix| has trailing whitespace or |suffix|
+ * has leading whitespace.
+ *
+ * A few examples:
+ *     CombineAndCollapseWhitespace('foo', 'bar', false)       -> 'foobar'
+ *     CombineAndCollapseWhitespace('foo', 'bar', true)        -> 'foo bar'
+ *     CombineAndCollapseWhitespace('foo ', 'bar', false)      -> 'foo bar'
+ *     CombineAndCollapseWhitespace('foo', ' bar', false)      -> 'foo bar'
+ *     CombineAndCollapseWhitespace('foo', ' bar', true)       -> 'foo bar'
+ *     CombineAndCollapseWhitespace('foo   ', '   bar', false) -> 'foo bar'
+ *     CombineAndCollapseWhitespace(' foo', 'bar ', false)     -> ' foobar '
+ *     CombineAndCollapseWhitespace(' foo', 'bar ', true)      -> ' foo bar '
+ *
+ * It is based on the logic in
+ * const string16 CombineAndCollapseWhitespace(const string16& prefix,
+ *                                             const string16& suffix,
+ *                                             bool force_whitespace)
+ * @param {string} prefix The prefix string in the string combination.
+ * @param {string} suffix The suffix string in the string combination.
+ * @param {boolean} forceWhitespace A boolean indicating if whitespace should
+ *     be added as separator in the combination.
+ * @return {string} The combined string.
+ */
+__gCrWeb.autofill.combineAndCollapseWhitespace = function(
+    prefix, suffix, forceWhitespace) {
+  var prefixTrimmed = __gCrWeb.autofill.trimWhitespaceTrailing(prefix);
+  var prefixTrailingWhitespace = prefixTrimmed != prefix;
+  var suffixTrimmed = __gCrWeb.autofill.trimWhitespaceLeading(suffix);
+  var suffixLeadingWhitespace = suffixTrimmed != suffix;
+  if (prefixTrailingWhitespace || suffixLeadingWhitespace || forceWhitespace) {
+    return prefixTrimmed + ' ' + suffixTrimmed;
+  } else {
+    return prefixTrimmed + suffixTrimmed;
+  }
+};
+
+/**
+ * This is a helper function for the findChildText() function (see below).
+ * Search depth is limited with the |depth| parameter.
+ * Based on form_autofill_util::findChildTextInner().
+ * @param {Element} node The node to fetch the text content from.
+ * @param {int} depth The maximum depth to descend on the DOM.
+ * @return {string} The discovered and adapted string.
+ */
+__gCrWeb.autofill.findChildTextInner = function(node, depth) {
+  if (depth <= 0 || !node) {
+    return '';
+  }
+
+  // Skip over comments.
+  if (node.nodeType === document.COMMENT_NODE) {
+    return __gCrWeb.autofill.findChildTextInner(node.nextSibling, depth - 1);
+  }
+
+  if (node.nodeType !== document.ELEMENT_NODE &&
+      node.nodeType !== document.TEXT_NODE) {
+    return '';
+  }
+
+  // Ignore elements known not to contain inferable labels.
+  if (node.nodeType === document.ELEMENT_NODE) {
+    if (node.tagName === 'OPTION' ||
+        node.tagName === 'SCRIPT' ||
+        node.tagName === 'NOSCRIPT' ||
+        (__gCrWeb.common.isFormControlElement(node) &&
+         __gCrWeb.autofill.isAutofillableElement(node))) {
+      return '';
+    }
+  }
+
+  // Extract the text exactly at this node.
+  var nodeText = __gCrWeb.autofill.nodeValue(node);
+  if (node.nodeType === document.TEXT_NODE && !nodeText) {
+    // In the C++ version, this text node would have been stripped completely.
+    // Just pass the buck.
+    return __gCrWeb.autofill.findChildTextInner(node.nextSibling, depth);
+  }
+
+  // Recursively compute the children's text.
+  // Preserve inter-element whitespace separation.
+  var childText =
+      __gCrWeb.autofill.findChildTextInner(node.firstChild, depth - 1);
+  var addSpace = node.nodeType === document.TEXT_NODE && !nodeText;
+  // Emulate apparently incorrect Chromium behavior tracked in crbug 239819.
+  addSpace = false;
+  nodeText = __gCrWeb.autofill.combineAndCollapseWhitespace(nodeText,
+      childText, addSpace);
+
+  // Recursively compute the siblings' text.
+  // Again, preserve inter-element whitespace separation.
+  var siblingText =
+      __gCrWeb.autofill.findChildTextInner(node.nextSibling, depth - 1);
+  addSpace = node.nodeType === document.TEXT_NODE && !nodeText;
+  // Emulate apparently incorrect Chromium behavior tracked in crbug 239819.
+  addSpace = false;
+  nodeText = __gCrWeb.autofill.combineAndCollapseWhitespace(nodeText,
+      siblingText, addSpace);
+
+  return nodeText;
+};
+
+/**
+ * Returns the aggregated values of the descendants of |element| that are
+ * non-empty text nodes.
+ *
+ * It is based on the logic in
+ *    string16 FindChildText(const WebNode& node)
+ * chromium/src/components/autofill/renderer/form_autofill_util.cc, which is a
+ * faster alternative to |innerText()| for performance critical operations.
+ *
+ * @param {Element} node A node of which the child text will be return.
+ * @return {string} The child text.
+ */
+__gCrWeb.autofill.findChildText = function(node) {
+  if (node.nodeType === document.TEXT_NODE)
+    return __gCrWeb.autofill.nodeValue(node);
+  var child = node.firstChild;
+
+  var kChildSearchDepth = 10;
+  var nodeText = __gCrWeb.autofill.findChildTextInner(child, kChildSearchDepth);
+  nodeText = nodeText.trim();
+  return nodeText;
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * a previous sibling of |element|,
+ * e.g. Some Text <input ...>
+ * or   Some <span>Text</span> <input ...>
+ * or   <p>Some Text</p><input ...>
+ * or   <label>Some Text</label> <input ...>
+ * or   Some Text <img><input ...>
+ * or   <b>Some Text</b><br/> <input ...>.
+ *
+ * It is based on the logic in
+ *     string16 InferLabelFromPrevious(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromPrevious = function(element) {
+  var inferredLabel = '';
+  var previous = element;
+  if (!previous) {
+    return '';
+  }
+
+  while (true) {
+    previous = previous.previousSibling;
+    if (!previous) {
+      break;
+    }
+
+    // Skip over comments.
+    var nodeType = previous.nodeType;
+    if (nodeType === document.COMMENT_NODE_NODE) {
+      continue;
+    }
+
+    // Otherwise, only consider normal HTML elements and their contents.
+    if (nodeType != document.TEXT_NODE &&
+        nodeType != document.ELEMENT_NODE) {
+      break;
+    }
+
+    // A label might be split across multiple "lightweight" nodes.
+    // Coalesce any text contained in multiple consecutive
+    //  (a) plain text nodes or
+    //  (b) inline HTML elements that are essentially equivalent to text nodes.
+    if (nodeType === document.TEXT_NODE ||
+        __gCrWeb.autofill.hasTagName(previous, 'b') ||
+        __gCrWeb.autofill.hasTagName(previous, 'strong') ||
+        __gCrWeb.autofill.hasTagName(previous, 'span') ||
+        __gCrWeb.autofill.hasTagName(previous, 'font')) {
+      var value = __gCrWeb.autofill.findChildText(previous);
+      // A text node's value will be empty if it is for a line break.
+      var addSpace = nodeType === document.TEXT_NODE &&
+          value.length === 0;
+      inferredLabel =
+          __gCrWeb.autofill.combineAndCollapseWhitespace(
+              value, inferredLabel, addSpace);
+      continue;
+    }
+
+    // If we have identified a partial label and have reached a non-lightweight
+    // element, consider the label to be complete.
+    var trimmedLabel = inferredLabel.trim();
+    if (trimmedLabel.length > 0) {
+      break;
+    }
+
+    // <img> and <br> tags often appear between the input element and its
+    // label text, so skip over them.
+    if (__gCrWeb.autofill.hasTagName(previous, 'img') ||
+        __gCrWeb.autofill.hasTagName(previous, 'br')) {
+      continue;
+    }
+
+    // We only expect <p> and <label> tags to contain the full label text.
+    if (__gCrWeb.autofill.hasTagName(previous, 'p') ||
+        __gCrWeb.autofill.hasTagName(previous, 'label')) {
+      inferredLabel = __gCrWeb.autofill.findChildText(previous);
+    }
+    break;
+  }
+  return inferredLabel.trim();
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * the placeholder attribute.
+ *
+ * It is based on the logic in
+ *     string16 InferLabelFromPlaceholder(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromPlaceholder = function(element) {
+  if (!element || !element.placeholder) {
+    return '';
+  }
+
+  return element.placeholder;
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * enclosing list item, e.g.
+ *     <li>Some Text<input ...><input ...><input ...></li>
+ *
+ * It is based on the logic in
+ *     string16 InferLabelFromListItem(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromListItem = function(element) {
+  if (!element) {
+    return '';
+  }
+
+  var parent = element.parentNode;
+  while (parent &&
+         parent.nodeType === document.ELEMENT_NODE &&
+         !__gCrWeb.autofill.hasTagName(parent, 'li')) {
+    parent = parent.parentNode;
+  }
+
+  if (parent && __gCrWeb.autofill.hasTagName(parent, 'li'))
+    return __gCrWeb.autofill.findChildText(parent);
+
+  return '';
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * surrounding table structure,
+ * e.g. <tr><td>Some Text</td><td><input ...></td></tr>
+ * or   <tr><th>Some Text</th><td><input ...></td></tr>
+ * or   <tr><td><b>Some Text</b></td><td><b><input ...></b></td></tr>
+ * or   <tr><th><b>Some Text</b></th><td><b><input ...></b></td></tr>
+ *
+ * It is based on the logic in
+ *    string16 InferLabelFromTableColumn(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromTableColumn = function(element) {
+  if (!element) {
+    return '';
+  }
+
+  var parent = element.parentNode;
+  while (parent &&
+         parent.nodeType === document.ELEMENT_NODE &&
+         !__gCrWeb.autofill.hasTagName(parent, 'td')) {
+    parent = parent.parentNode;
+  }
+
+  if (!parent) {
+    return '';
+  }
+
+  // Check all previous siblings, skipping non-element nodes, until we find a
+  // non-empty text block.
+  var inferredLabel = '';
+  var previous = parent.previousSibling;
+  while (inferredLabel.length === 0 && previous) {
+    if (__gCrWeb.autofill.hasTagName(previous, 'td') ||
+        __gCrWeb.autofill.hasTagName(previous, 'th')) {
+      inferredLabel = __gCrWeb.autofill.findChildText(previous);
+    }
+    previous = previous.previousSibling;
+  }
+
+  return inferredLabel;
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * surrounding table structure,
+ * e.g. <tr><td>Some Text</td></tr><tr><td><input ...></td></tr>
+ *
+ * It is based on the logic in
+ *     string16 InferLabelFromTableRow(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromTableRow = function(element) {
+  if (!element) {
+    return '';
+  }
+
+  var parent = element.parentNode;
+  while (parent &&
+         parent.nodeType === document.ELEMENT_NODE &&
+         !__gCrWeb.autofill.hasTagName(parent, 'tr')) {
+    parent = parent.parentNode;
+  }
+
+  if (!parent) {
+    return '';
+  }
+
+  var inferredLabel = '';
+  // Check all previous siblings, skipping non-element nodes, until we find a
+  // non-empty text block.
+  var previous = parent.previousSibling;
+  while (inferredLabel.length === 0 && previous) {
+    if (__gCrWeb.autofill.hasTagName(previous, 'tr')) {
+      inferredLabel = __gCrWeb.autofill.findChildText(previous);
+    }
+    previous = previous.previousSibling;
+  }
+  return inferredLabel;
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * a surrounding div table,
+ * e.g. <div>Some Text<span><input ...></span></div>
+ * e.g. <div>Some Text</div><div><input ...></div>
+ *
+ * It is based on the logic in
+ *    string16 InferLabelFromDivTable(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromDivTable = function(element) {
+  if (!element) {
+    return '';
+  }
+
+  var node = element.parentNode;
+  var lookingForParent = true;
+
+  // Search the sibling and parent <div>s until we find a candidate label.
+  var inferredLabel = '';
+  while (inferredLabel.length === 0 && node) {
+    if (__gCrWeb.autofill.hasTagName(node, 'div')) {
+      lookingForParent = false;
+      inferredLabel = __gCrWeb.autofill.findChildText(node);
+    } else if (lookingForParent &&
+        (__gCrWeb.autofill.hasTagName(node, 'table') ||
+            __gCrWeb.autofill.hasTagName(node, 'fieldset'))) {
+      // If the element is in a table or fieldset, its label most likely is too.
+      break;
+    }
+
+    if (!node.previousSibling) {
+      // If there are no more siblings, continue walking up the tree.
+      lookingForParent = true;
+    }
+
+    if (lookingForParent) {
+      node = node.parentNode;
+    } else {
+      node = node.previousSibling;
+    }
+  }
+
+  return inferredLabel;
+};
+
+/**
+ * Helper for |InferLabelForElement()| that infers a label, if possible, from
+ * a surrounding definition list,
+ * e.g. <dl><dt>Some Text</dt><dd><input ...></dd></dl>
+ * e.g. <dl><dt><b>Some Text</b></dt><dd><b><input ...></b></dd></dl>
+ *
+ * It is based on the logic in
+ *    string16 InferLabelFromDefinitionList(
+ *        const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelFromDefinitionList = function(element) {
+  if (!element) {
+    return '';
+  }
+
+  var parent = element.parentNode;
+  while (parent &&
+         parent.nodeType === document.ELEMENT_NODE &&
+         !__gCrWeb.autofill.hasTagName(parent, 'dd')) {
+    parent = parent.parentNode;
+  }
+
+  if (!parent || !__gCrWeb.autofill.hasTagName(parent, 'dd')) {
+    return '';
+  }
+
+  // Skip by any intervening text nodes.
+  var previous = parent.previousSibling;
+  while (previous &&
+         previous.nodeType === document.TEXT_NODE) {
+    previous = previous.previousSibling;
+  }
+
+  if (!previous || !__gCrWeb.autofill.hasTagName(previous, 'dt'))
+    return '';
+
+  return __gCrWeb.autofill.findChildText(previous);
+};
+
+/**
+ * Infers corresponding label for |element| from surrounding context in the DOM,
+ * e.g. the contents of the preceding <p> tag or text element.
+ *
+ * It is based on the logic in
+ *    string16 InferLabelForElement(const WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The label of element.
+ */
+__gCrWeb.autofill.inferLabelForElement = function(element) {
+  var inferredLabel = __gCrWeb.autofill.inferLabelFromPrevious(element);
+  if (inferredLabel.length > 0) {
+    return inferredLabel;
+  }
+
+  // If we didn't find a label, check for the placeholder case.
+  inferredLabel = __gCrWeb.autofill.inferLabelFromPlaceholder(element);
+  if (inferredLabel.length > 0) {
+    return inferredLabel;
+  }
+
+  // If we didn't find a label, check for list item case.
+  inferredLabel = __gCrWeb.autofill.inferLabelFromListItem(element);
+  if (inferredLabel.length > 0) {
+    return inferredLabel;
+  }
+
+  // If we didn't find a label, check for table cell case.
+  inferredLabel = __gCrWeb.autofill.inferLabelFromTableColumn(element);
+  if (inferredLabel.length > 0) {
+    return inferredLabel;
+  }
+
+  // If we didn't find a label, check for table row case.
+  inferredLabel = __gCrWeb.autofill.inferLabelFromTableRow(element);
+  if (inferredLabel.length > 0) {
+    return inferredLabel;
+  }
+
+  // If we didn't find a label, check for definition list case.
+  inferredLabel = __gCrWeb.autofill.inferLabelFromDefinitionList(element);
+  if (inferredLabel.length > 0) {
+    return inferredLabel;
+  }
+
+  // If we didn't find a label, check for div table case.
+  return __gCrWeb.autofill.inferLabelFromDivTable(element);
+};
+
+/**
+ * Fills |field| data with the values of the <option> elements present in
+ * |selectElement|.
+ *
+ * It is based on the logic in
+ *     void GetOptionStringsFromElement(const WebSelectElement& select_element,
+ *                                      std::vector<string16>* option_values,
+ *                                      std::vector<string16>* option_contents)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * @param {Element} selectElement A select element from which option data are
+ *     extracted.
+ * @param {Object} field A field that will contain the extracted option
+ *     information.
+ */
+__gCrWeb.autofill.getOptionStringsFromElement = function(
+    selectElement, field) {
+  field['option_values'] = [];
+  // Protect against custom implementation of Array.toJSON in host pages.
+  field['option_values'].toJSON = null;
+  field['option_contents'] = [];
+  field['option_contents'].toJSON = null;
+  var options = selectElement.options;
+  for (var i = 0; i < options.length; ++i) {
+    var option = options[i];
+    field['option_values'].push(option['value']);
+    field['option_contents'].push(option['text']);
+  }
+};
+
+/**
+ * Sets the |field|'s value to the value in |data|.
+ * Also sets the "autofilled" attribute.
+ *
+ * It is based on the logic in
+ *     void FillFormField(const FormFieldData& data,
+ *                        bool is_initiating_node,
+ *                        blink::WebFormControlElement* field)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.cc.
+ *
+ * Different from FillFormField(), is_initiating_node is not considered in
+ * this implementation.
+ *
+ * @param {Object} data Data that will be filled into field.
+ * @param {Element} field The element to which data will be filled.
+ */
+__gCrWeb.autofill.fillFormField = function(data, field) {
+  // Nothing to fill.
+  if (!data['value'] || data['value'].length === 0) {
+    return;
+  }
+
+  if (__gCrWeb.autofill.isTextInput(field) ||
+      __gCrWeb.autofill.isTextAreaElement(field)) {
+    var sanitizedValue = data['value'];
+
+    if (__gCrWeb.autofill.isTextInput(field)) {
+      // If the 'max_length' attribute contains a negative value, the default
+      // maxlength value is used.
+      var maxLength = data['max_length'];
+      if (maxLength < 0) {
+        maxLength = __gCrWeb.autofill.MAX_DATA_LENGTH;
+      }
+      sanitizedValue = data['value'].substr(0, maxLength);
+    }
+
+    __gCrWeb.common.setInputElementValue(sanitizedValue, field, true);
+    field.isAutofilled = true;
+  } else if (__gCrWeb.autofill.isSelectElement(field)) {
+    if (field.value !== data['value']) {
+      field.value = data['value'];
+      __gCrWeb.common.createAndDispatchHTMLEvent(field, 'change', true, false);
+    }
+  } else {
+    if (__gCrWeb.autofill.isCheckableElement(field)) {
+      __gCrWeb.common.setInputElementChecked(data['is_checked'], field, true);
+    }
+  }
+};
+
+/**
+ * Returns true if |element| is a text input element.
+ *
+ * It is based on the logic in
+ *     bool IsTextInput(const blink::WebInputElement* element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} element An element to examine.
+ * @return {boolean} Whether element is a text input field.
+ */
+__gCrWeb.autofill.isTextInput = function(element) {
+  if (!element) {
+    return false;
+  }
+  return __gCrWeb.common.isTextField(element);
+};
+
+/**
+ * Returns true if |element| is a 'select' element.
+ *
+ * It is based on the logic in
+ *     bool IsSelectElement(const blink::WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} element An element to examine.
+ * @return {boolean} Whether element is a 'select' element.
+ */
+__gCrWeb.autofill.isSelectElement = function(element) {
+  if (!element) {
+    return false;
+  }
+  return element.type === 'select-one';
+};
+
+/**
+ * Returns true if |element| is a 'textarea' element.
+ *
+ * It is based on the logic in
+ *     bool IsTextAreaElement(const blink::WebFormControlElement& element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} element An element to examine.
+ * @return {boolean} Whether element is a 'textarea' element.
+ */
+__gCrWeb.autofill.isTextAreaElement = function(element) {
+  if (!element) {
+    return false;
+  }
+  return element.type === 'textarea';
+};
+
+/**
+ * Returns true if |element| is a checkbox or a radio button element.
+ *
+ * It is based on the logic in
+ *     bool IsCheckableElement(const blink::WebInputElement* element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} element An element to examine.
+ * @return {boolean} Whether element is a checkbox or a radio button.
+ */
+__gCrWeb.autofill.isCheckableElement = function(element) {
+  if (!element) {
+    return false;
+  }
+  return element.type === 'checkbox' || element.type === 'radio';
+};
+
+/**
+ * Returns true if |element| is one of the input element types that can be
+ * autofilled. {Text, Radiobutton, Checkbox}.
+ *
+ * It is based on the logic in
+ *    bool IsAutofillableInputElement(const blink::WebInputElement* element)
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} element An element to examine.
+ * @return {boolean} Whether element is one of the input element types that
+ *     can be autofilled.
+ */
+__gCrWeb.autofill.isAutofillableInputElement = function(element) {
+  return __gCrWeb.autofill.isTextInput(element) ||
+         __gCrWeb.autofill.isCheckableElement(element);
+};
+
+/**
+ * Returns the nodeValue in a way similar to the C++ version of node.nodeValue,
+ * used in src/components/autofill/renderer/form_autofill_util.h. Newlines and
+ * tabs are stripped.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The text contained in |element|.
+ */
+__gCrWeb.autofill.nodeValue = function(element) {
+  return (element.nodeValue || '').replace(/[\n\t]/gm, '');
+};
+
+/**
+ * Returns the value in a way similar to the C++ version of node.value,
+ * used in src/components/autofill/renderer/form_autofill_util.h. Newlines and
+ * tabs are stripped.
+ *
+ * @param {Element} element An element to examine.
+ * @return {string} The value for |element|.
+ */
+__gCrWeb.autofill.value = function(element) {
+  return (element.value || '').replace(/[\n\t]/gm, '');
+};
+
+/**
+ * Returns the auto-fillable form control elements in |formElement|.
+ *
+ * It is based on the logic in
+ *     void ExtractAutofillableElements(
+ *         const blink::WebFormElement& form_element,
+ *         RequirementsMask requirements,
+ *         std::vector<blink::WebFormControlElement>* autofillable_elements);
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} formElement A form element to be processed.
+ * @param {int} requirementsMask A mask on the requirement.
+ * @param {Array.<Element>} autofillableElements The array of autofillable
+ *     elements.
+ */
+__gCrWeb.autofill.extractAutofillableElements = function(
+    formElement, requirementsMask, autofillableElements) {
+  var controlElements = __gCrWeb.common.getFormControlElements(formElement);
+
+  for (var i = 0; i < controlElements.length; ++i) {
+    var element = controlElements[i];
+    if (!__gCrWeb.autofill.isAutofillableElement(element)) {
+      continue;
+    }
+    if (requirementsMask &
+        __gCrWeb.autofill.REQUIREMENTS_MASK_REQUIRE_AUTOCOMPLETE) {
+      // Different from method void ExtractAutofillableElements() in
+      // chromium/src/components/autofill/renderer/form_autofill_util.h, where
+      // satisfiesRequireAutocomplete() check is only applied on input controls,
+      // here satisfiesRequireAutocomplete() check is also applied on select
+      // control element. This is based on the TODO in that file saying "WebKit
+      // currently doesn't handle the autocomplete attribute for select control
+      // elements, but it probably should."
+      if (!__gCrWeb.autofill.satisfiesRequireAutocomplete(element, false)) {
+        continue;
+      }
+    }
+    autofillableElements.push(element);
+  }
+};
+
+/**
+ * Fills out a FormField object from a given form control element.
+ *
+ * It is based on the logic in
+ *     void WebFormControlElementToFormField(
+ *         const blink::WebFormControlElement& element,
+ *         ExtractMask extract_mask,
+ *         FormFieldData* field);
+ * in chromium/src/components/autofill/renderer/form_autofill_util.h.
+ *
+ * @param {Element} element The element to be processed.
+ * @param {int} extractMask A bit field mask to extract data from |element|.
+ *     See the document on variable __gCrWeb.autofill.EXTRACT_MASK_NONE,
+ *     __gCrWeb.autofill.EXTRACT_MASK_VALUE,
+ *     __gCrWeb.autofill.EXTRACT_MASK_OPTION_TEXT and
+ *     __gCrWeb.autofill.EXTRACT_MASK_OPTIONS.
+ * @param {Object} field Field to fill in the element information.
+ */
+__gCrWeb.autofill.webFormControlElementToFormField = function(
+    element, extractMask, field) {
+  if (!field || !element) {
+    return;
+  }
+  // The label is not officially part of a form control element; however, the
+  // labels for all form control elements are scraped from the DOM and set in
+  // form data.
+  field['name'] = __gCrWeb['common'].nameForAutofill(element);
+  field['form_control_type'] = element.type;
+  var attribute = element.getAttribute('autocomplete');
+  if (attribute) {
+    field['autocomplete_attribute'] = attribute;
+  }
+  if (field['autocomplete_attribute'] != null &&
+      field['autocomplete_attribute'].length >
+          __gCrWeb.autofill.MAX_DATA_LENGTH) {
+    // Discard overly long attribute values to avoid DOS-ing the browser
+    // process. However, send over a default string to indicate that the
+    // attribute was present.
+    field['autocomplete_attribute'] = 'x-max-data-length-exceeded';
+  }
+
+  if (!__gCrWeb.autofill.isAutofillableElement(element)) {
+    return;
+  }
+
+  if (__gCrWeb.autofill.isAutofillableInputElement(element) ||
+          __gCrWeb.autofill.isTextAreaElement(element)) {
+    field['is_autofilled'] = element.isAutofilled;
+    field['should_autocomplete'] = __gCrWeb.common.autoComplete(element);
+    // TODO(chenyu): compute this item properly.
+    // field['is_focusable'] = element.isFocusable;
+  }
+
+  if (__gCrWeb.autofill.isAutofillableInputElement(element)) {
+    if (__gCrWeb.autofill.isTextInput(element)) {
+      field['max_length'] = element.maxLength;
+    }
+    field['is_checkable'] = __gCrWeb.autofill.isCheckableElement(element);
+  } else if (__gCrWeb.autofill.isTextAreaElement(element)) {
+    // Nothing more to do in this case.
+  } else if (extractMask & __gCrWeb.autofill.EXTRACT_MASK_OPTIONS) {
+    __gCrWeb.autofill.getOptionStringsFromElement(element, field);
+  }
+
+  if (!extractMask & __gCrWeb.autofill.EXTRACT_MASK_VALUE) {
+    return;
+  }
+
+  var value = __gCrWeb.autofill.value(element);
+
+  if (!__gCrWeb.autofill.isAutofillableInputElement(element)) {
+    // Convert the |select_element| value to text if requested.
+    if (extractMask & __gCrWeb.autofill.EXTRACT_MASK_OPTION_TEXT) {
+      var options = element.options;
+      for (var index = 0; index < options.length; ++index) {
+        var optionElement = options[index];
+        if (__gCrWeb.autofill.value(optionElement) === value) {
+          value = optionElement.text;
+          break;
+        }
+      }
+    }
+  }
+
+  // There is a constraint on the maximum data length in method
+  // WebFormControlElementToFormField() in form_autofill_util.h in order to
+  // prevent a malicious site from DOS'ing the browser: http://crbug.com/49332,
+  // which isn't really meaningful here, but we need to follow the same logic to
+  // get the same form signature wherever possible (to get the benefits of the
+  // existing crowdsourced field detection corpus).
+  if (value.length > __gCrWeb.autofill.MAX_DATA_LENGTH) {
+    value = value.substr(0, __gCrWeb.autofill.MAX_DATA_LENGTH);
+  }
+  field['value'] = value;
+};
+
+/**
+ * For debugging purposes, annotate forms on the page with prediction data using
+ * the placeholder attribute.
+ *
+ * @param {Object} data The form and field identifiers with their prection data.
+ */
+__gCrWeb.autofill['fillPredictionData'] = function(data) {
+
+  for (formName in data) {
+    var form = __gCrWeb.common.getFormElementFromIdentifier(formName);
+    var formData = data[formName];
+    var controlElements = __gCrWeb.common.getFormControlElements(form);
+    for (var i = 0; i < controlElements.length; ++i) {
+      var element = controlElements[i];
+      if (!__gCrWeb.autofill.isAutofillableElement(element)) {
+        continue;
+      }
+      var elementName = __gCrWeb['common'].nameForAutofill(element);
+      var value = formData[elementName];
+      if (value) {
+        element.placeholder = value;
+      }
+    }
+  }
+};