Report types as strings

This CL improves the readability of votes uploads:
Before the CL, you would see "autofill_type: [51]".
After the CL, you now see "autofill_type: [51/CREDIT_CARD_NAME_FULL]".

If std::vector<std::string> elements are piped into the LogBuffer,
these are automatically represented as a comma separated list
in the output.

R=kolos@chromium.org

Bug: 928595
Change-Id: I68c917be57c5dbf32a7932235b8c52dc8916cf97
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1724521
Commit-Queue: Dominic Battré <battre@chromium.org>
Reviewed-by: Maxim Kolosovskiy <kolos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#682537}

components/autofill/core/browser/autofill_download_manager.cc

@@ -381,6 +381,12 @@ std::ostream& operator<<(std::ostream& out,
   return out;
 }
 
+std::string FieldTypeToString(int type) {
+  return base::StrCat(
+      {base::NumberToString(type), std::string("/"),
+       AutofillType(static_cast<ServerFieldType>(type)).ToString()});
+}
+
 LogBuffer& operator<<(LogBuffer& out,
                       const autofill::AutofillUploadContents& upload) {
   if (!out.active())
@@ -411,9 +417,11 @@ LogBuffer& operator<<(LogBuffer& out,
     out << Tr{} << Attrib{"style", "font-weight: bold"}
         << "field_signature:" << field.signature();
 
-    LogBuffer autofill_type;
-    autofill_type << Tag{"span"} << field.autofill_type();
-    out << Tr{} << "autofill_type:" << std::move(autofill_type);
+    std::vector<std::string> types_as_strings;
+    types_as_strings.reserve(field.autofill_type_size());
+    for (int type : field.autofill_type())
+      types_as_strings.emplace_back(FieldTypeToString(type));
+    out << Tr{} << "autofill_type:" << types_as_strings;
 
     LogBuffer validities;
     validities << Tag{"span"} << "[";

components/autofill/core/browser/logging/log_buffer.h

@@ -166,6 +166,18 @@ LogBuffer& operator<<(LogBuffer& buf,
   return buf;
 }
 
+template <typename T>
+LogBuffer& operator<<(LogBuffer& buf, const std::vector<T>& values) {
+  buf << "[";
+  for (size_t i = 0; i < values.size(); ++i) {
+    if (i)
+      buf << ", ";
+    buf << values.at(i);
+  }
+  buf << "]";
+  return buf;
+}
+
 // This is syntactic sugar for creating table rows in a LogBuffer. Each
 // value streamed into this LogTableRowBuffer is wrapped by a <td> element.
 // The entire row is wrapped by a <tr>.