Use absl::NoDestructor for static flat_hash_map

PiperOrigin-RevId: 671853605

sharing/internal/base/BUILD

@@ -34,6 +34,7 @@ cc_library(
     ],
     visibility = ["//visibility:public"],
     deps = [
+        "@com_google_absl//absl/base:no_destructor",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/types:span",

sharing/internal/base/mime.cc

@@ -16,6 +16,7 @@
 
 #include <string>
 
+#include "absl/base/no_destructor.h"
 #include "absl/container/flat_hash_map.h"
 #include "absl/strings/ascii.h"
 #include "absl/strings/string_view.h"
@@ -27,10 +28,9 @@ namespace utils {
 // http://svn.apache.org/repos/asf/httpd/httpd/trunk/docs/conf/mime.types.
 std::string GetWellKnownMimeTypeFromExtension(absl::string_view extension) {
   // The extension types in this map must be lower case.
-  static absl::flat_hash_map<
+  static absl::NoDestructor<absl::flat_hash_map<
       std::string,
-      std::string>* mime_map = new absl::flat_hash_map<std::string,
-                                                       std::string>({
+      std::string>> mime_map({
       {"123", "application/vnd.lotus-1-2-3"},
       {"3dml", "text/vnd.in3d.3dml"},
       {"3ds", "image/x-3ds"},