Convert easy bits of HttpUtil to StringPiece.

Most of this file is awkwardly tied up with prtime.cc or
StringTokenizer, but convert some boring ones.

Bug: 820198
Change-Id: I339911e7cfbe6136a82d71ec1d1cd000ccc7b91a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1575873
Auto-Submit: David Benjamin <davidben@chromium.org>
Reviewed-by: Eric Roman <eroman@chromium.org>
Commit-Queue: David Benjamin <davidben@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652640}

net/http/http_util.cc

@@ -421,18 +421,18 @@ const char* const kForbiddenHeaderFields[] = {
 }  // namespace
 
 // static
-bool HttpUtil::IsMethodSafe(const std::string& method) {
+bool HttpUtil::IsMethodSafe(base::StringPiece method) {
   return method == "GET" || method == "HEAD" || method == "OPTIONS" ||
          method == "TRACE";
 }
 
 // static
-bool HttpUtil::IsMethodIdempotent(const std::string& method) {
+bool HttpUtil::IsMethodIdempotent(base::StringPiece method) {
   return IsMethodSafe(method) || method == "PUT" || method == "DELETE";
 }
 
 // static
-bool HttpUtil::IsSafeHeader(const std::string& name) {
+bool HttpUtil::IsSafeHeader(base::StringPiece name) {
   std::string lower_name(base::ToLowerASCII(name));
   if (base::StartsWith(lower_name, "proxy-", base::CompareCase::SENSITIVE) ||
       base::StartsWith(lower_name, "sec-", base::CompareCase::SENSITIVE))
@@ -446,13 +446,13 @@ bool HttpUtil::IsSafeHeader(const std::string& name) {
 }
 
 // static
-bool HttpUtil::IsValidHeaderName(const base::StringPiece& name) {
+bool HttpUtil::IsValidHeaderName(base::StringPiece name) {
   // Check whether the header name is RFC 2616-compliant.
   return HttpUtil::IsToken(name);
 }
 
 // static
-bool HttpUtil::IsValidHeaderValue(const base::StringPiece& value) {
+bool HttpUtil::IsValidHeaderValue(base::StringPiece value) {
   // Just a sanity check: disallow NUL, CR and LF.
   for (char c : value) {
     if (c == '\0' || c == '\r' || c == '\n')

net/http/http_util.h

@@ -87,22 +87,22 @@ class NET_EXPORT HttpUtil {
 
   // Returns true if the request method is "safe" (per section 4.2.1 of
   // RFC 7231).
-  static bool IsMethodSafe(const std::string& method);
+  static bool IsMethodSafe(base::StringPiece method);
 
   // Returns true if the request method is idempotent (per section 4.2.2 of
   // RFC 7231).
-  static bool IsMethodIdempotent(const std::string& method);
+  static bool IsMethodIdempotent(base::StringPiece method);
 
   // Returns true if it is safe to allow users and scripts to specify the header
   // named |name|.
-  static bool IsSafeHeader(const std::string& name);
+  static bool IsSafeHeader(base::StringPiece name);
 
   // Returns true if |name| is a valid HTTP header name.
-  static bool IsValidHeaderName(const base::StringPiece& name);
+  static bool IsValidHeaderName(base::StringPiece name);
 
   // Returns false if |value| contains NUL or CRLF. This method does not perform
   // a fully RFC-2616-compliant header value validation.
-  static bool IsValidHeaderValue(const base::StringPiece& value);
+  static bool IsValidHeaderValue(base::StringPiece value);
 
   // Multiple occurances of some headers cannot be coalesced into a comma-
   // separated list since their values are (or contain) unquoted HTTP-date