Autofill: Improve the order of heuristics to apply when inferring labels

Right now the order is somewhat arbitrary. Instead, look at the types of
a field's ancestors to determine the order.

BUG=465587

Review URL: https://codereview.chromium.org/1012093004

Cr-Commit-Position: refs/heads/master@{#321249}

4 files changed, 76 insertions, 74 deletions

diff --git a/chrome/test/data/autofill/heuristics/output/12_register_officedepot.com.out b/chrome/test/data/autofill/heuristics/output/12_register_officedepot.com.out
index d5132a5..f94b063 100644
--- a/chrome/test/data/autofill/heuristics/output/12_register_officedepot.com.out
+++ b/chrome/test/data/autofill/heuristics/output/12_register_officedepot.com.out
@@ -3,7 +3,7 @@ NAME_MIDDLE_INITIAL | addrsForm[0].middleInitial | Middle Initial: |  | addrsFor
 NAME_LAST | addrsForm[0].lastName | *Last Name: |  | addrsForm[0].firstName_1-default
 COMPANY_NAME | addrsForm[0].shiptoName | Company Name |  | addrsForm[0].firstName_1-default
 ADDRESS_HOME_LINE1 | addrsForm[0].address1 | *Address |  | addrsForm[0].firstName_1-default
-ADDRESS_HOME_LINE2 | addrsForm[0].address2 | *First Name:Middle Initial:*Last Name:Company Name |  | addrsForm[0].firstName_1-default
+ADDRESS_HOME_LINE2 | addrsForm[0].address2 |  |  | addrsForm[0].firstName_1-default
 ADDRESS_HOME_CITY | addrsForm[0].city | *City |  | addrsForm[0].firstName_1-default
 ADDRESS_HOME_STATE | addrsForm[0].state | *State | {blank} | addrsForm[0].firstName_1-default
 ADDRESS_HOME_ZIP | addrsForm[0].postalCode1 | *Zip Code |  | addrsForm[0].firstName_1-default
@@ -26,7 +26,7 @@ NAME_MIDDLE_INITIAL | addrsForm[2].middleInitial | Middle Initial: |  | addrsFor
 NAME_LAST | addrsForm[2].lastName | *Last Name: |  | addrsForm[2].firstName_1-default
 COMPANY_NAME | addrsForm[2].shiptoName | Company Name |  | addrsForm[2].firstName_1-default
 ADDRESS_HOME_LINE1 | addrsForm[2].address1 | *Address |  | addrsForm[2].firstName_1-default
-ADDRESS_HOME_LINE2 | addrsForm[2].address2 | * Indicates required field *First Name:Middle Initial:*Last Name:Company Name |  | addrsForm[2].firstName_1-default
+ADDRESS_HOME_LINE2 | addrsForm[2].address2 |  |  | addrsForm[2].firstName_1-default
 ADDRESS_HOME_CITY | addrsForm[2].city | *City |  | addrsForm[2].firstName_1-default
 ADDRESS_HOME_STATE | addrsForm[2].state | *State | {blank} | addrsForm[2].firstName_1-default
 ADDRESS_HOME_ZIP | addrsForm[2].postalCode1 | *Zip Code |  | addrsForm[2].firstName_1-default
diff --git a/chrome/test/data/autofill/heuristics/output/20_register_epson.com.mx.out b/chrome/test/data/autofill/heuristics/output/20_register_epson.com.mx.out
index 3c6a52f..8d33cc7 100644
--- a/chrome/test/data/autofill/heuristics/output/20_register_epson.com.mx.out
+++ b/chrome/test/data/autofill/heuristics/output/20_register_epson.com.mx.out
@@ -1,5 +1,5 @@
 UNKNOWN_TYPE | doAction |  |  | doAction_1-default
-ADDRESS_HOME_COUNTRY | idPaiseReg | n del producto *dd/mm/yyyySerial *Acerca del nro. de Serie | MX | doAction_1-default
+ADDRESS_HOME_COUNTRY | idPaiseReg |  | MX | doAction_1-default
 UNKNOWN_TYPE | fechaCompra | *dd/mm/yyyy |  | doAction_1-default
 UNKNOWN_TYPE | serialNumber | Serial * |  | doAction_1-default
 UNKNOWN_TYPE | idProducto | Serial * |  | doAction_1-default
diff --git a/chrome/test/data/autofill/heuristics/output/bug_465587.out b/chrome/test/data/autofill/heuristics/output/bug_465587.out
index ed43f40..7bc8116 100644
--- a/chrome/test/data/autofill/heuristics/output/bug_465587.out
+++ b/chrome/test/data/autofill/heuristics/output/bug_465587.out
@@ -2,30 +2,30 @@ UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.
 UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType | Paypal | payPalPayment | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
 UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType | Gift Certificate | giftCertificate | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
 CREDIT_CARD_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.creditCardType | Credit Card Type | visa | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
-CREDIT_CARD_NAME | cardholder | Credit Card Type |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
-CREDIT_CARD_NUMBER | cardnumber | Credit Card Type |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
-CREDIT_CARD_EXP_MONTH | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.expirationMonth | Credit Card Type | 01 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
-CREDIT_CARD_EXP_4_DIGIT_YEAR | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.expirationYear | Credit Card Type | 2015 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
-CREDIT_CARD_TYPE | secureid | Credit Card Type |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
-UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.billingSameAsShipping | Credit Card Type | true | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
-CREDIT_CARD_NAME | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName | First Name |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-cc
-UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.lastName | Last Name |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.militaryAddressInd | APO FPO DPO | APO | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.militaryAddressInd | APO | FPO | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.militaryAddressInd | FPO | DPO | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_COUNTRY | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.country | Country | US | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_LINE1 | address1 | Address |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_LINE2 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.address2 | Address |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_CITY | city | City |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-ADDRESS_HOME_ZIP | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.postalCode | Zip / Postal Code |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-PHONE_HOME_WHOLE_NUMBER | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.phoneNumber | Phone |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/commerce/cart/item/3281003514/item_qty | Optimum Nutrition Gold Standard 100% Whey Delicious Strawberry, 1 Lb. $14.98 | 1 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/shipping/group/sg1157540843 | 1 Day Delivers in 1 business day $16.48 | 1 Day (Order By 3:00 p.m. PST) | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/shipping/group/sg1157540843 | 2 Day Delivers in 2 business days $11.98 | 2 Day | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/shipping/group/sg1157540843 | Standard Delivers in 2-3 business days $5.97 | Standard (3-5 Days) | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.isSignupNewsletter | Orders are subject to Bodybuilding.com'sTerms of Use and Privacy Policy. | true | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
-UNKNOWN_TYPE | formhandler | Orders are subject to Bodybuilding.com'sTerms of Use and Privacy Policy. | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName_1-default
+CREDIT_CARD_NAME | cardholder | Cardholder Name |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
+CREDIT_CARD_NUMBER | cardnumber | Credit Card Number |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
+CREDIT_CARD_EXP_MONTH | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.expirationMonth | Expiration Date | 01 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
+CREDIT_CARD_EXP_4_DIGIT_YEAR | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.expirationYear | Expiration Date | 2015 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
+CREDIT_CARD_VERIFICATION_CODE | secureid | CVC/CVV |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-cc
+UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.billingSameAsShipping |  | true | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+NAME_FIRST | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.firstName | First Name |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+NAME_LAST | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.lastName | Last Name |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.militaryAddressInd | APO FPO DPO | APO | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.militaryAddressInd | APO | FPO | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.militaryAddressInd | FPO | DPO | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_COUNTRY | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.country | Country | US | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_LINE1 | address1 | Address |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_LINE2 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.address2 | Address |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_CITY | city | City |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_STATE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.state | State: |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+ADDRESS_HOME_ZIP | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.postalCode | Zip / Postal Code |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+PHONE_HOME_WHOLE_NUMBER | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.creditCard.billingAddress.phoneNumber | Phone |  | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/commerce/cart/item/3281003514/item_qty | Optimum Nutrition Gold Standard 100% Whey Delicious Strawberry, 1 Lb. $14.98 | 1 | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/shipping/group/sg1157540843 | 1 Day Delivers in 1 business day $16.48 | 1 Day (Order By 3:00 p.m. PST) | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/shipping/group/sg1157540843 | 2 Day Delivers in 2 business days $11.98 | 2 Day | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/shipping/group/sg1157540843 | Standard Delivers in 2-3 business days $5.97 | Standard (3-5 Days) | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.isSignupNewsletter | Orders are subject to Bodybuilding.com'sTerms of Use and Privacy Policy. | true | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
+UNKNOWN_TYPE | formhandler | Orders are subject to Bodybuilding.com'sTerms of Use and Privacy Policy. | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler | /bodybuilding/commerce/order/purchase/CardPaymentInfoFormHandler.billingInfo.paymentType_1-default
diff --git a/components/autofill/content/renderer/form_autofill_util.cc b/components/autofill/content/renderer/form_autofill_util.cc
index 90fa11f..91d3572 100644
--- a/components/autofill/content/renderer/form_autofill_util.cc
+++ b/components/autofill/content/renderer/form_autofill_util.cc
@@ -129,6 +129,21 @@ bool IsElementInsideFormOrFieldSet(const WebElement& element) {
   return false;
 }
 
+// Returns true if |node| is an element and it is a container type that
+// InferLabelForElement() can traverse.
+bool IsTraversableContainerElement(const WebNode& node) {
+  if (!node.isElementNode())
+    return false;
+
+  std::string tag_name = node.toConst<WebElement>().tagName().utf8();
+  return (tag_name == "DD" ||
+          tag_name == "DIV" ||
+          tag_name == "FIELDSET" ||
+          tag_name == "LI" ||
+          tag_name == "TD" ||
+          tag_name == "TABLE");
+}
+
 // Check whether the given field satisfies the REQUIRE_AUTOCOMPLETE requirement.
 bool SatisfiesRequireAutocomplete(const WebInputElement& input_element) {
   return input_element.autoComplete();
@@ -546,8 +561,6 @@ base::string16 InferLabelFromDivTable(const WebFormControlElement& element) {
   // Search the sibling and parent <div>s until we find a candidate label.
   base::string16 inferred_label;
   CR_DEFINE_STATIC_LOCAL(WebString, kDiv, ("div"));
-  CR_DEFINE_STATIC_LOCAL(WebString, kTable, ("table"));
-  CR_DEFINE_STATIC_LOCAL(WebString, kFieldSet, ("fieldset"));
   CR_DEFINE_STATIC_LOCAL(WebString, kLabel, ("label"));
   while (inferred_label.empty() && !node.isNull()) {
     if (HasTagName(node, kDiv)) {
@@ -573,9 +586,8 @@ base::string16 InferLabelFromDivTable(const WebFormControlElement& element) {
       WebLabelElement label_element = node.to<WebLabelElement>();
       if (label_element.correspondingControl().isNull())
         inferred_label = FindChildText(node);
-    } else if (looking_for_parent &&
-               (HasTagName(node, kTable) || HasTagName(node, kFieldSet))) {
-      // If the element is in a table or fieldset, its label most likely is too.
+    } else if (looking_for_parent && IsTraversableContainerElement(node)) {
+      // If the element is in a non-div container, its label most likely is too.
       break;
     }
 
@@ -617,23 +629,20 @@ base::string16 InferLabelFromDefinitionList(
   return FindChildText(previous);
 }
 
-// Returns true if the closest ancestor is a <div> and not a <td>.
-// Returns false if the closest ancestor is a <td> tag,
-// or if there is no <div> or <td> ancestor.
-bool ClosestAncestorIsDivAndNotTD(const WebFormControlElement& element) {
+// Returns the element type for all ancestor nodes in CAPS, starting with the
+// parent node.
+std::vector<std::string> AncestorTagNames(
+    const WebFormControlElement& element) {
+  std::vector<std::string> tag_names;
   for (WebNode parent_node = element.parentNode();
        !parent_node.isNull();
        parent_node = parent_node.parentNode()) {
     if (!parent_node.isElementNode())
       continue;
 
-    WebElement cur_element = parent_node.to<WebElement>();
-    if (cur_element.hasHTMLTagName("div"))
-      return true;
-    if (cur_element.hasHTMLTagName("td"))
-      return false;
+    tag_names.push_back(parent_node.to<WebElement>().tagName().utf8());
   }
-  return false;
+  return tag_names;
 }
 
 // Infers corresponding label for |element| from surrounding context in the DOM,
@@ -655,40 +664,33 @@ base::string16 InferLabelForElement(const WebFormControlElement& element) {
   if (!inferred_label.empty())
     return inferred_label;
 
-  // If we didn't find a label, check for list item case.
-  inferred_label = InferLabelFromListItem(element);
-  if (!inferred_label.empty())
-    return inferred_label;
+  // For all other searches that involve traversing up the tree, the search
+  // order is based on which tag is the closest ancestor to |element|.
+  std::vector<std::string> tag_names = AncestorTagNames(element);
+  std::set<std::string> seen_tag_names;
+  for (const std::string& tag_name : tag_names) {
+    if (ContainsKey(seen_tag_names, tag_name))
+      continue;
 
-  // If we didn't find a label, check for definition list case.
-  inferred_label = InferLabelFromDefinitionList(element);
-  if (!inferred_label.empty())
-    return inferred_label;
+    seen_tag_names.insert(tag_name);
+    if (tag_name == "DIV") {
+      inferred_label = InferLabelFromDivTable(element);
+    } else if (tag_name == "TD") {
+      inferred_label = InferLabelFromTableColumn(element);
+      if (inferred_label.empty())
+        inferred_label = InferLabelFromTableRow(element);
+    } else if (tag_name == "DD") {
+      inferred_label = InferLabelFromDefinitionList(element);
+    } else if (tag_name == "LI") {
+      inferred_label = InferLabelFromListItem(element);
+    } else if (tag_name == "FIELDSET") {
+      break;
+    }
 
-  bool check_div_first = ClosestAncestorIsDivAndNotTD(element);
-  if (check_div_first) {
-    // If we didn't find a label, check for div table case first since it's the
-    // closest ancestor.
-    inferred_label = InferLabelFromDivTable(element);
     if (!inferred_label.empty())
-      return inferred_label;
+      break;
   }
 
-  // If we didn't find a label, check for table cell case.
-  inferred_label = InferLabelFromTableColumn(element);
-  if (!inferred_label.empty())
-    return inferred_label;
-
-  // If we didn't find a label, check for table row case.
-  inferred_label = InferLabelFromTableRow(element);
-  if (!inferred_label.empty())
-    return inferred_label;
-
-  if (!check_div_first) {
-    // If we didn't find a label from the table, check for div table case if we
-    // haven't already.
-    inferred_label = InferLabelFromDivTable(element);
-  }
   return inferred_label;
 }