Pass more hints to encoding detector.

third_party/WebKit/Source/platform/text/TextEncodingDetectorTest.cpp

 // Copyright 2016 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 "platform/text/TextEncodingDetector.h"
 
 #include "testing/gtest/include/gtest/gtest.h"
 #include "wtf/text/TextEncoding.h"
 
 namespace blink {
 
 TEST(TextResourceDecoderTest, RespectIso2022Jp) {
   // ISO-2022-JP is the only 7-bit encoding defined in WHATWG standard.
   std::string iso2022jp =
       " \x1B"
       "$BKL3$F;F|K\\%O%`%U%!%$%?!<%:$,%=%U%H%P%s%/$H$N%W%l!<%*%U$r@)$7!\"";
   WTF::TextEncoding encoding;
   bool result = detectTextEncoding(iso2022jp.c_str(), iso2022jp.length(),
-                                   nullptr, &encoding);
+                                   nullptr, String(), nullptr, &encoding);
   EXPECT_TRUE(result);
   EXPECT_EQ(WTF::TextEncoding("ISO-2022-JP"), encoding);
 }
 
 TEST(TextResourceDecoderTest, Ignore7BitEncoding) {
   // 7-bit encodings except ISO-2022-JP are not supported by WHATWG.
   // They should be detected as plain text (US-ASCII).
   std::string hzGb2312 =
       " ~{\x54\x42\x31\x7D\x37\x22\x55\x39\x35\x3D\x3D\x71~} abc";
   WTF::TextEncoding encoding;
   bool result = detectTextEncoding(hzGb2312.c_str(), hzGb2312.length(), nullptr,
-                                   &encoding);
+                                   String(), nullptr, &encoding);
   EXPECT_TRUE(result);
   EXPECT_EQ(WTF::TextEncoding("US-ASCII"), encoding);
 }
 
+TEST(TextEncodingDetectorTest, UrlHintHelpsEUCJP) {

[Jinsuk Kim, 2017/01/20 21:50:47]

Can you add another EXPECT to show that additional hints help improve the
detection accuracy? Like detectTextEncoding without hints returning an encoding
which is not expected - like GBK as reported in the bug.

[tkent, 2017/01/23 00:02:57]

Done.

+  std::string eucjpBytes =
+      "<TITLE>"
+      "\xA5\xD1\xA5\xEF\xA1\xBC\xA5\xC1\xA5\xE3\xA1\xBC\xA5\xC8\xA1\xC3\xC5\xEA"
+      "\xBB\xF1\xBE\xF0\xCA\xF3\xA4\xCE\xA5\xD5\xA5\xA3\xA5\xB9\xA5\xB3</"
+      "TITLE>";
+  WTF::TextEncoding encoding;
+  bool result =
+      detectTextEncoding(eucjpBytes.c_str(), eucjpBytes.length(), nullptr,
+                         "http://example.co.jp/", nullptr, &encoding);
+  EXPECT_TRUE(result);
+  EXPECT_EQ(WTF::TextEncoding("EUC-JP"), encoding);
+}
+
+TEST(TextEncodingDetectorTest, LanguageHintHelpsEUCJP) {
+  std::string eucjpBytes =
+      "<TITLE>"
+      "\xA5\xD1\xA5\xEF\xA1\xBC\xA5\xC1\xA5\xE3\xA1\xBC\xA5\xC8\xA1\xC3\xC5\xEA"
+      "\xBB\xF1\xBE\xF0\xCA\xF3\xA4\xCE\xA5\xD5\xA5\xA3\xA5\xB9\xA5\xB3</"
+      "TITLE>";
+  WTF::TextEncoding encoding;
+  bool result = detectTextEncoding(eucjpBytes.c_str(), eucjpBytes.length(),
+                                   nullptr, String(), "ja", &encoding);
+  EXPECT_TRUE(result);
+  EXPECT_EQ(WTF::TextEncoding("EUC-JP"), encoding);
+}
+
 }  // namespace blink