Update from chromium https://crrev.com/304586

base/i18n/streaming_utf8_validator_perftest.cc

Index: base/i18n/streaming_utf8_validator_perftest.cc
diff --git a/base/i18n/streaming_utf8_validator_perftest.cc b/base/i18n/streaming_utf8_validator_perftest.cc
index ac2eb0820bac01a3a172fb89236d92a9763562e9..6b8c17b654b1a8c279b43ea2d8c7b89702b81210 100644
--- a/base/i18n/streaming_utf8_validator_perftest.cc
+++ b/base/i18n/streaming_utf8_validator_perftest.cc
@@ -134,6 +134,10 @@ struct TestFunctionDescription {
   const char* function_name;
 };
 
+bool IsStringUTF8(const std::string& str) {
+  return base::IsStringUTF8(base::StringPiece(str));
+}
+
 // IsString7Bit is intentionally placed last so it can be excluded easily.
 const TestFunctionDescription kTestFunctions[] = {
     {&StreamingUtf8Validator::Validate, "StreamingUtf8Validator"},