Clean up to move NewStringCopy from util to chromoes/string.

src/common/chromeos/string.h

Index: src/common/chromeos/string.h
diff --git a/src/common/chromeos/string.h b/src/common/chromeos/string.h
index 9c1394a068d91c0d6db6cad248df10da65ee3282..be330d2009610065dcbd2d3aa611eb5a26601484 100644
--- a/src/common/chromeos/string.h
+++ b/src/common/chromeos/string.h
@@ -16,6 +16,10 @@ void SplitStringUsing(const std::string& str,
                       const std::string& delim,
                       std::vector<std::string>* parts);
 
+// Copies the string. Use delete (not delete [] or free) to release the returned
+// string.
+char* NewStringCopy(const char* x);
+
 }  // namespace chromeos
 
 #endif /* CHROMEOS_STRING_H_ */