[Fetch] Always use utf-8 for decoding in text()

third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h

Index: third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h
diff --git a/third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h b/third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h
index 2539cc8a68577c5e20da2b757637e3e510931e27..8d894b5bf81d49abb83a062d03559d16457ae676 100644
--- a/third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h
+++ b/third_party/WebKit/Source/core/html/parser/TextResourceDecoder.h
@@ -46,9 +46,18 @@ public:
         EncodingFromParentFrame
     };
 
-    static PassOwnPtr<TextResourceDecoder> create(const String& mimeType, const WTF::TextEncoding& defaultEncoding = WTF::TextEncoding(), bool usesEncodingDetector = false)
+    enum BOMCheckOptions {
+        CheckForAllBOM,
+        // create("text/plain", UTF8Encoding(), false, CheckForOnlyUTF8BOM)
+        // always uses UTF8Encoding() and omits utf-8 BOM, and thus
+        // corresponds to utf-8 decode in Encoding spec:
+        // https://encoding.spec.whatwg.org/#utf-8-decode
+        CheckForOnlyUTF8BOM
+    };
+
+    static PassOwnPtr<TextResourceDecoder> create(const String& mimeType, const WTF::TextEncoding& defaultEncoding = WTF::TextEncoding(), bool usesEncodingDetector = false, BOMCheckOptions bomCheckOptions = CheckForAllBOM)
     {
-        return adoptPtr(new TextResourceDecoder(mimeType, defaultEncoding, usesEncodingDetector));
+        return adoptPtr(new TextResourceDecoder(mimeType, defaultEncoding, usesEncodingDetector, bomCheckOptions));
     }
     ~TextResourceDecoder();
 
@@ -73,7 +82,7 @@ public:
     size_t checkForBOM(const char*, size_t);
 
 private:
-    TextResourceDecoder(const String& mimeType, const WTF::TextEncoding& defaultEncoding, bool usesEncodingDetector);
+    TextResourceDecoder(const String& mimeType, const WTF::TextEncoding& defaultEncoding, bool usesEncodingDetector, BOMCheckOptions);
 
     enum ContentType { PlainTextContent, HTMLContent, XMLContent, CSSContent }; // PlainText only checks for BOM.
     static ContentType determineContentType(const String& mimeType);
@@ -97,6 +106,7 @@ private:
     bool m_useLenientXMLDecoding; // Don't stop on XML decoding errors.
     bool m_sawError;
     bool m_usesEncodingDetector;
+    BOMCheckOptions m_bomCheckOptions;
 
     OwnPtr<HTMLMetaCharsetParser> m_charsetParser;
 };