Tweaking WebPageSerializerImpl to emit a BOM for UTF16/32.

third_party/WebKit/Source/wtf/text/TextEncoding.cpp

Index: third_party/WebKit/Source/wtf/text/TextEncoding.cpp
diff --git a/third_party/WebKit/Source/wtf/text/TextEncoding.cpp b/third_party/WebKit/Source/wtf/text/TextEncoding.cpp
index 3b0563887861bc7145b7422c056fe2fc2fca2e15..76aa25a60bb7a718a1145ce0ad4022d60ed7e4f0 100644
--- a/third_party/WebKit/Source/wtf/text/TextEncoding.cpp
+++ b/third_party/WebKit/Source/wtf/text/TextEncoding.cpp
@@ -84,6 +84,18 @@ CString TextEncoding::encode(const String& string, UnencodableHandling handling)
     return encodedString;
 }
 
+CString TextEncoding::encodeBOMifApplicable() const
+{
+    // TODO(lukasza): Store |textCodec| in a member field, so it can be reused
+    // across repeated calls to encode and/or encodeBOMifApplicable.

[jsbell, 2015/12/07 22:53:51]

That would change the behavior for stateful encodings, unfortunately.

Callers can use TextCodec directly if that level of control is desired. (e.g.
Source/modules/TextEncoding.cpp)

+    OwnPtr<TextCodec> textCodec = newTextCodec(*this);
+    if (!textCodec->shouldIncludeBOM())
+        return "";
+
+    const UChar bomCharacter = 0xFEFF;
+    return textCodec->encode(&bomCharacter, 1, QuestionMarksForUnencodables);
+}
+
 bool TextEncoding::usesVisualOrdering() const
 {
     if (noExtendedTextEncodingNameUsed())