Do not guess UTF8 encoding

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 {
@@ skipping 55 matching lines @@
   EXPECT_EQ(WTF::TextEncoding("GBK"), encoding)
       << "Without language hint, it's detected as GBK";
 
   result = detectTextEncoding(eucjpBytes.c_str(), eucjpBytes.length(), nullptr,
                               nullptr, "ja", &encoding);
   EXPECT_TRUE(result);
   EXPECT_EQ(WTF::TextEncoding("EUC-JP"), encoding)
       << "With language hint 'ja', it's detected as EUC-JP";
 }
 
+TEST(TextEncodingDetectorTest, UTF8DetectionShouldFail) {
+  std::string utf8Bytes =
+      "tnegirjji gosa gii beare s\xC3\xA1htt\xC3\xA1 \xC4\x8D\xC3"
+      "\xA1llit artihkkaliid. Maid don s\xC3\xA1ht\xC3\xA1t dievasmah";
+  WTF::TextEncoding encoding;
+  bool result = detectTextEncoding(utf8Bytes.c_str(), utf8Bytes.length(),
+                                   nullptr, nullptr, nullptr, &encoding);
+  EXPECT_FALSE(result);
+}
+
 }  // namespace blink