[autofill] Support angularjs select with "string:" prefix.

AngularJS can prefix the value in select elements with a type
prefix. Autofill already supports teh "number:" prefix. This
CL adds support for "string:".

Bug: 770781
Change-Id: I5c2b272ca20a3f3a68e3445166c0df36ad5aa058
Reviewed-on: https://chromium-review.googlesource.com/695941
Commit-Queue: Roger McFarlane <rogerm@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Reviewed-by: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#505774}

components/autofill/core/browser/autofill_field.cc

@@ -200,15 +200,18 @@ bool FillExpirationMonthSelectControl(const base::string16& value,
   if (!StringToInt(value, &month) || month <= 0 || month > 12)
     return false;
 
-  // We trim the whitespace and a specific prefix used in AngularJS from the
+  // Trim the whitespace and specific prefixes used in AngularJS from the
   // select values before attempting to convert them to months.
   std::vector<base::string16> trimmed_values(field->option_values.size());
   const base::string16 kNumberPrefix = ASCIIToUTF16("number:");
+  const base::string16 kStringPrefix = ASCIIToUTF16("string:");
   for (size_t i = 0; i < field->option_values.size(); ++i) {
     base::TrimWhitespace(field->option_values[i], base::TRIM_ALL,
                          &trimmed_values[i]);
     base::ReplaceFirstSubstringAfterOffset(&trimmed_values[i], 0, kNumberPrefix,
                                            ASCIIToUTF16(""));
+    base::ReplaceFirstSubstringAfterOffset(&trimmed_values[i], 0, kStringPrefix,
+                                           ASCIIToUTF16(""));
   }
 
   if (trimmed_values.size() == 12) {

components/autofill/core/browser/autofill_field_unittest.cc

@@ -705,13 +705,18 @@ INSTANTIATE_TEST_CASE_P(
             {"00", "01", "02", "03", "04", "05", "06", "07", "08", "09", "10",
              "11"},
             NotNumericMonthsContentsNoPlaceholder()},
-        // The AngularJS framework adds a prefix to number types. Test that it
-        // is removed.
+        // The AngularJS framework can add a "number:" prefix to select values.
         FillWithExpirationMonthTestCase{
             {"number:1", "number:2", "number:3", "number:4", "number:5",
              "number:6", "number:7", "number:8", "number:9", "number:10",
              "number:11", "number:12"},
             NotNumericMonthsContentsNoPlaceholder()},
+        // The AngularJS framework can add a "string:" prefix to select values.
+        FillWithExpirationMonthTestCase{
+            {"string:1", "string:2", "string:3", "string:4", "string:5",
+             "string:6", "string:7", "string:8", "string:9", "string:10",
+             "string:11", "string:12"},
+            NotNumericMonthsContentsNoPlaceholder()},
         // Values start at 0 and the first content is a placeholder.
         FillWithExpirationMonthTestCase{
             {"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11",