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

Source/platform/network/HTTPParsersTest.cpp

Index: Source/platform/network/HTTPParsersTest.cpp
diff --git a/Source/platform/network/HTTPParsersTest.cpp b/Source/platform/network/HTTPParsersTest.cpp
index 9831f2edc1bcc8143555c23195db2f92df6d5c35..b558b7473b1664749ed39810f2d712ebe27f63a7 100644
--- a/Source/platform/network/HTTPParsersTest.cpp
+++ b/Source/platform/network/HTTPParsersTest.cpp
@@ -223,5 +223,22 @@ TEST(HTTPParsersTest, parseHTTPHeaderTwoLines)
     EXPECT_EQ("fuga", value.string());
 }
 
+TEST(HTTPParsersTest, CommaDelimitedHeaderSet)
+{
+    CommaDelimitedHeaderSet set1;
+    CommaDelimitedHeaderSet set2;
+    parseCommaDelimitedHeader("dpr, rw, whatever", set1);
+    EXPECT_TRUE(set1.contains("dpr"));
+    EXPECT_TRUE(set1.contains("rw"));
+    EXPECT_TRUE(set1.contains("whatever"));
+    parseCommaDelimitedHeader("dprw\t     , fo\to", set2);
+    EXPECT_FALSE(set2.contains("dpr"));
+    EXPECT_FALSE(set2.contains("rw"));
+    EXPECT_FALSE(set2.contains("whatever"));
+    EXPECT_TRUE(set2.contains("dprw"));
+    EXPECT_FALSE(set2.contains("foo"));
+    EXPECT_TRUE(set2.contains("fo\to"));
+}
+
 } // namespace blink