Implement IsAsciiUpper and IsAsciiLower in base/strings/string_util.h

url/url_file.h

Index: url/url_file.h
diff --git a/url/url_file.h b/url/url_file.h
index 540cb2543eb8cf9b37f95b6cfb8b0034f107a218..796d12c1880832e22d489c3ed4fc8f3a3e67813a 100644
--- a/url/url_file.h
+++ b/url/url_file.h
@@ -8,6 +8,7 @@
 // Provides shared functions used by the internals of the parser and
 // canonicalizer for file URLs. Do not use outside of these modules.
 
+#include "base/strings/string_util.h"
 #include "url/url_parse_internal.h"
 
 namespace url {
@@ -18,9 +19,6 @@ namespace url {
 inline bool IsWindowsDriveSeparator(base::char16 ch) {
   return ch == ':' || ch == '|';
 }
-inline bool IsWindowsDriveLetter(base::char16 ch) {
-  return (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z');
-}
 
 #endif  // WIN32
 
@@ -48,7 +46,7 @@ inline bool DoesBeginWindowsDriveSpec(const CHAR* spec, int start_offset,
   int remaining_len = spec_len - start_offset;
   if (remaining_len < 2)
     return false;  // Not enough room.
-  if (!IsWindowsDriveLetter(spec[start_offset]))
+  if (!base::IsAsciiAlpha(spec[start_offset]))
     return false;  // Doesn't start with a valid drive letter.
   if (!IsWindowsDriveSeparator(spec[start_offset + 1]))
     return false;  // Isn't followed with a drive separator.