Pull in ASCII<->UTF16 from Chromium

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 39974b4b2b8f539085e117c93af223c053b08a28..29368d38a659ab0ae4f62b7062e9f52789e3c98b 100644
--- a/base/strings/utf_string_conversions.cc
+++ b/base/strings/utf_string_conversions.cc
@@ -8,7 +8,9 @@
 
 #include <string>
 
+#include "base/logging.h"
 #include "base/strings/string16.h"
+#include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversion_utils.h"
 
 namespace {
@@ -58,4 +60,13 @@ std::string UTF16ToUTF8(const string16& utf16) {
   return ret;
 }
 
+string16 ASCIIToUTF16(const StringPiece& ascii) {
+  DCHECK(IsStringASCII(ascii)) << ascii;
+  return string16(ascii.begin(), ascii.end());
+}
+
+std::string UTF16ToASCII(const string16& utf16) {
+  DCHECK(IsStringASCII(utf16)) << UTF16ToUTF8(utf16);
+  return std::string(utf16.begin(), utf16.end());
+}
 }  // namespace