Align base::hash_map with C++11.

base/files/file_path.h

Index: base/files/file_path.h
diff --git a/base/files/file_path.h b/base/files/file_path.h
index 008b9f5afc67d83db10decbcc9447723da40fbdd..68908662cdf6f6d956e7353ee592640f2bfbb4b1 100644
--- a/base/files/file_path.h
+++ b/base/files/file_path.h
@@ -453,7 +453,6 @@ BASE_EXPORT extern void PrintTo(const base::FilePath& path, std::ostream* out);
 // Provide a hash function so that hash_sets and maps can contain FilePath
 // objects.
 namespace BASE_HASH_NAMESPACE {
-#if defined(COMPILER_GCC)
 
 template<>
 struct hash<base::FilePath> {
@@ -462,14 +461,6 @@ struct hash<base::FilePath> {
   }
 };
 
-#elif defined(COMPILER_MSVC)
-
-inline size_t hash_value(const base::FilePath& f) {
-  return hash_value(f.value());
-}
-
-#endif  // COMPILER
-
 }  // namespace BASE_HASH_NAMESPACE
 
 #endif  // BASE_FILES_FILE_PATH_H_