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

net/http/http_response_headers.cc

Index: net/http/http_response_headers.cc
diff --git a/net/http/http_response_headers.cc b/net/http/http_response_headers.cc
index 659b3ca3fba820be8ef24da72c2ba4dd3d429c22..2f89d1f3024b8721dfd2e7fdb83e4e8e765f8602 100644
--- a/net/http/http_response_headers.cc
+++ b/net/http/http_response_headers.cc
@@ -655,7 +655,7 @@ HttpVersion HttpResponseHeaders::ParseVersion(
   ++p;  // from / to first digit.
   ++dot;  // from . to second digit.
 
-  if (!(*p >= '0' && *p <= '9' && *dot >= '0' && *dot <= '9')) {
+  if (!(base::IsAsciiDigit(*p) && base::IsAsciiDigit(*dot))) {
     DVLOG(1) << "malformed version number";
     return HttpVersion();
   }
@@ -710,7 +710,7 @@ void HttpResponseHeaders::ParseStatusLine(
     ++p;
 
   std::string::const_iterator code = p;
-  while (p < line_end && *p >= '0' && *p <= '9')
+  while (p < line_end && base::IsAsciiDigit(*p))
     ++p;
 
   if (p == code) {