Use #if DCHECK_IS_ON() in base/strings/string_piece.*

base/strings/string_piece.h

Index: base/strings/string_piece.h
diff --git a/base/strings/string_piece.h b/base/strings/string_piece.h
index c1af175406c23419f051232e3dcfc1f6f8d7fb83..eb82d336ff1005c1dc0f41d933a7192d7c37e853 100644
--- a/base/strings/string_piece.h
+++ b/base/strings/string_piece.h
@@ -30,6 +30,7 @@
 #include "base/base_export.h"
 #include "base/basictypes.h"
 #include "base/containers/hash_tables.h"
+#include "base/logging.h"
 #include "base/strings/string16.h"
 
 namespace base {
@@ -143,7 +144,7 @@ BASE_EXPORT StringPiece16 substr(const StringPiece16& self,
                                  size_t pos,
                                  size_t n);
 
-#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+#if DCHECK_IS_ON()
 // Asserts that begin <= end to catch some errors with iterator usage.
 BASE_EXPORT void AssertIteratorsInOrder(std::string::const_iterator begin,
                                         std::string::const_iterator end);
@@ -189,7 +190,7 @@ template <typename STRING_TYPE> class BasicStringPiece {
       : ptr_(offset), length_(len) {}
   BasicStringPiece(const typename STRING_TYPE::const_iterator& begin,
                    const typename STRING_TYPE::const_iterator& end) {
-#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+#if DCHECK_IS_ON()
     // This assertion is done out-of-line to avoid bringing in logging.h and
     // instantiating logging macros for every instantiation.
     internal::AssertIteratorsInOrder(begin, end);