Remove legacy StartsWithASCII function.

extensions/browser/guest_view/web_view/web_view_guest.cc

Index: extensions/browser/guest_view/web_view/web_view_guest.cc
diff --git a/extensions/browser/guest_view/web_view/web_view_guest.cc b/extensions/browser/guest_view/web_view/web_view_guest.cc
index 1ee9252e392997ae23c48fd33d4073ef38bcbff1..a71fda99f6c3a35f240c26d6a487a9ce45d760bb 100644
--- a/extensions/browser/guest_view/web_view/web_view_guest.cc
+++ b/extensions/browser/guest_view/web_view/web_view_guest.cc
@@ -153,7 +153,8 @@ void ParsePartitionParam(const base::DictionaryValue& create_params,
   // UTF-8 encoded |partition_id|. If the prefix is a match, we can safely
   // remove the prefix without splicing in the middle of a multi-byte codepoint.
   // We can use the rest of the string as UTF-8 encoded one.
-  if (base::StartsWithASCII(partition_str, "persist:", true)) {
+  if (base::StartsWith(partition_str, "persist:",
+                       base::CompareCase::SENSITIVE)) {
     size_t index = partition_str.find(":");
     CHECK(index != std::string::npos);
     // It is safe to do index + 1, since we tested for the full prefix above.