wstring: remove wstring version of RemoveChars

base/string_util.h

Index: base/string_util.h
diff --git a/base/string_util.h b/base/string_util.h
index 0b52ac044845cc0f3a7ccc24d7cedf850f122b5c..0cb439cb5fa1c8b8e34a589c66984bfdc15bd02f 100644
--- a/base/string_util.h
+++ b/base/string_util.h
@@ -180,9 +180,6 @@ BASE_API extern const char kUtf8ByteOrderMark[];
 // Removes characters in remove_chars from anywhere in input.  Returns true if
 // any characters were removed.
 // NOTE: Safe to use the same variable for both input and output.
-BASE_API bool RemoveChars(const std::wstring& input,
-                          const wchar_t remove_chars[],
-                          std::wstring* output);
 BASE_API bool RemoveChars(const string16& input,
                           const char16 remove_chars[],
                           string16* output);