net: add IsMethodSafe() method to HttpUtil

net/http/http_util.cc

Index: net/http/http_util.cc
diff --git a/net/http/http_util.cc b/net/http/http_util.cc
index b1ff9443b64ff32d0ef5db88cb9ea2a652ef587e..5f7c8531e8828d9914a1d2e7bf8e5288eb20b6c9 100644
--- a/net/http/http_util.cc
+++ b/net/http/http_util.cc
@@ -345,6 +345,12 @@ const char* const kForbiddenHeaderFields[] = {
 }  // namespace
 
 // static
+bool HttpUtil::IsMethodSafe(const std::string& method) {
+  return method == "GET" || method == "HEAD" || method == "OPTIONS" ||
+         method == "TRACE";
+}
+
+// static
 bool HttpUtil::IsSafeHeader(const std::string& name) {
   std::string lower_name(base::ToLowerASCII(name));
   if (base::StartsWith(lower_name, "proxy-", base::CompareCase::SENSITIVE) ||