Update from https://crrev.com/307664

base/strings/utf_string_conversions.cc

Index: base/strings/utf_string_conversions.cc
diff --git a/base/strings/utf_string_conversions.cc b/base/strings/utf_string_conversions.cc
index 9796eec5e15e40966c4d9c435f6832c6fea715c9..1480d48086fed618ffbcc95cf918d8a0c1ebcb7e 100644
--- a/base/strings/utf_string_conversions.cc
+++ b/base/strings/utf_string_conversions.cc
@@ -209,11 +209,6 @@ std::string UTF16ToUTF8(const string16& utf16) {
 
 #endif
 
-std::wstring ASCIIToWide(const StringPiece& ascii) {
-  DCHECK(IsStringASCII(ascii)) << ascii;
-  return std::wstring(ascii.begin(), ascii.end());
-}
-
 string16 ASCIIToUTF16(const StringPiece& ascii) {
   DCHECK(IsStringASCII(ascii)) << ascii;
   return string16(ascii.begin(), ascii.end());