Update from https://crrev.com/315085

base/strings/string_util.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/strings/string_util.h"
 
 #include <ctype.h>
 #include <errno.h>
 #include <math.h>
 #include <stdarg.h>
@@ skipping 436 matching lines @@
                           const char* b) {
   return DoLowerCaseEqualsASCII(a_begin, a_end, b);
 }
 
 bool LowerCaseEqualsASCII(string16::const_iterator a_begin,
                           string16::const_iterator a_end,
                           const char* b) {
   return DoLowerCaseEqualsASCII(a_begin, a_end, b);
 }
 
-// TODO(port): Resolve wchar_t/iterator issues that require OS_ANDROID here.
-#if !defined(OS_ANDROID)
+// TODO(jdduke): Remove guards after complete adoption of libc++ on Android.
+#if !defined(OS_ANDROID) || !defined(USE_STLPORT)
 bool LowerCaseEqualsASCII(const char* a_begin,
                           const char* a_end,
                           const char* b) {
   return DoLowerCaseEqualsASCII(a_begin, a_end, b);
 }
 
 bool LowerCaseEqualsASCII(const char16* a_begin,
                           const char16* a_end,
                           const char* b) {
   return DoLowerCaseEqualsASCII(a_begin, a_end, b);
 }
-
-#endif  // !defined(OS_ANDROID)
+#endif  // !defined(OS_ANDROID) || !defined(USE_STLPORT)
 
 bool EqualsASCII(const string16& a, const base::StringPiece& b) {
   if (a.length() != b.length())
     return false;
   return std::equal(b.begin(), b.end(), a.begin());
 }
 
 bool StartsWithASCII(const std::string& str,
                      const std::string& search,
                      bool case_sensitive) {
@@ skipping 467 matching lines @@
 }
 
 }  // namespace
 
 size_t base::strlcpy(char* dst, const char* src, size_t dst_size) {
   return lcpyT<char>(dst, src, dst_size);
 }
 size_t base::wcslcpy(wchar_t* dst, const wchar_t* src, size_t dst_size) {
   return lcpyT<wchar_t>(dst, src, dst_size);
 }