Align base::hash_map with C++11.

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 a051bc8e9010dac76db797a50a59738d79477c6b..349018b9d0a25116755ee948f3007d0bba07175e 100644
--- a/base/strings/string_piece.h
+++ b/base/strings/string_piece.h
@@ -439,7 +439,6 @@ BASE_EXPORT std::ostream& operator<<(std::ostream& o,
   return result;                                                        \
 
 namespace BASE_HASH_NAMESPACE {
-#if defined(COMPILER_GCC)
 
 template<>
 struct hash<base::StringPiece> {
@@ -454,17 +453,6 @@ struct hash<base::StringPiece16> {
   }
 };
 
-#elif defined(COMPILER_MSVC)
-
-inline size_t hash_value(const base::StringPiece& sp) {
-  HASH_STRING_PIECE(base::StringPiece, sp);
-}
-inline size_t hash_value(const base::StringPiece16& sp16) {
-  HASH_STRING_PIECE(base::StringPiece16, sp16);
-}
-
-#endif  // COMPILER
-
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // BASE_STRINGS_STRING_PIECE_H_