Use the single char overload of append() when possible.

third_party/WebKit/Source/modules/websockets/DOMWebSocketTest.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "modules/websockets/DOMWebSocket.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "bindings/core/v8/V8Binding.h"
 #include "bindings/core/v8/V8BindingForTesting.h"
 #include "core/dom/DOMTypedArray.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/SecurityContext.h"
 #include "core/fileapi/Blob.h"
 #include "core/inspector/ConsoleTypes.h"
 #include "core/testing/DummyPageHolder.h"
 #include "platform/heap/Handle.h"
 #include "public/platform/WebInsecureRequestPolicy.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "wtf/Vector.h"
 #include "wtf/text/CString.h"
+#include "wtf/text/StringBuilder.h"
 #include "wtf/text/WTFString.h"
 #include <memory>
 #include <v8.h>
 
 using testing::_;
 using testing::AnyNumber;
 using testing::InSequence;
 using testing::Ref;
 using testing::Return;
 
@@ skipping 318 matching lines @@
 
 TEST(DOMWebSocketTest, maximumReasonSize)
 {
     V8TestingScope scope;
     DOMWebSocketTestScope webSocketScope(scope.getExecutionContext());
     {
         InSequence s;
         EXPECT_CALL(webSocketScope.channel(), connect(KURL(KURL(), "ws://example.com/"), String())).WillOnce(Return(true));
         EXPECT_CALL(webSocketScope.channel(), failMock(_, _, _));
     }
-    String reason;
+    StringBuilder reason;
     for (size_t i = 0; i < 123; ++i)
-        reason.append("a");
+        reason.append('a');
     webSocketScope.socket().connect("ws://example.com/", Vector<String>(), scope.getExceptionState());
 
     EXPECT_FALSE(scope.getExceptionState().hadException());
     EXPECT_EQ(DOMWebSocket::CONNECTING, webSocketScope.socket().readyState());
 
-    webSocketScope.socket().close(1000, reason, scope.getExceptionState());
+    webSocketScope.socket().close(1000, reason.toString(), scope.getExceptionState());
 
     EXPECT_FALSE(scope.getExceptionState().hadException());
     EXPECT_EQ(DOMWebSocket::CLOSING, webSocketScope.socket().readyState());
 }
 
 TEST(DOMWebSocketTest, reasonSizeExceeding)
 {
     V8TestingScope scope;
     DOMWebSocketTestScope webSocketScope(scope.getExecutionContext());
     {
         InSequence s;
         EXPECT_CALL(webSocketScope.channel(), connect(KURL(KURL(), "ws://example.com/"), String())).WillOnce(Return(true));
     }
-    String reason;
+    StringBuilder reason;
     for (size_t i = 0; i < 124; ++i)
-        reason.append("a");
+        reason.append('a');
     webSocketScope.socket().connect("ws://example.com/", Vector<String>(), scope.getExceptionState());
 
     EXPECT_FALSE(scope.getExceptionState().hadException());
     EXPECT_EQ(DOMWebSocket::CONNECTING, webSocketScope.socket().readyState());
 
-    webSocketScope.socket().close(1000, reason, scope.getExceptionState());
+    webSocketScope.socket().close(1000, reason.toString(), scope.getExceptionState());
 
     EXPECT_TRUE(scope.getExceptionState().hadException());
     EXPECT_EQ(SyntaxError, scope.getExceptionState().code());
     EXPECT_EQ("The message must not be greater than 123 bytes.", scope.getExceptionState().message());
     EXPECT_EQ(DOMWebSocket::CONNECTING, webSocketScope.socket().readyState());
 }
 
 TEST(DOMWebSocketTest, closeWhenConnecting)
 {
     V8TestingScope scope;
@@ skipping 406 matching lines @@
     EXPECT_EQ(InvalidAccessError, scope.getExceptionState().code());
     EXPECT_EQ(String::format("The code must be either 1000, or between 3000 and 4999. %d is neither.", GetParam()), scope.getExceptionState().message());
     EXPECT_EQ(DOMWebSocket::CONNECTING, webSocketScope.socket().readyState());
 }
 
 INSTANTIATE_TEST_CASE_P(DOMWebSocketInvalidClosingCode, DOMWebSocketInvalidClosingCodeTest, ::testing::Values(0, 1, 998, 999, 1001, 2999, 5000, 9999, 65535));
 
 } // namespace
 
 } // namespace blink