Add a comma delimited syntax parser and use it for Accept-CH

Source/platform/CommaDelimitedParserTest.cpp

+// Copyright 2015 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 "config.h"
+#include "CommaDelimitedParser.h"
+
+#include <gtest/gtest.h>
+
+namespace blink {
+
+TEST(CommaDelimitedParserTest, Basic)
+{
+    {
+        CommaDelimitedParser parser("dpr, rw, whatever");
+        EXPECT_TRUE(parser.contains("dpr"));
+        EXPECT_TRUE(parser.contains("rw"));
+        EXPECT_TRUE(parser.contains("whatever"));
+    }
+    {
+        CommaDelimitedParser parser("dprw\t     , fo\to");
+        EXPECT_FALSE(parser.contains("dpr"));
+        EXPECT_FALSE(parser.contains("rw"));
+        EXPECT_FALSE(parser.contains("whatever"));
+        EXPECT_TRUE(parser.contains("dprw"));
+        EXPECT_FALSE(parser.contains("foo"));
+        EXPECT_TRUE(parser.contains("fo\to"));
+    }
+}
+
+} // namespace blink
+