CookieStoreManager: be explicit about destructor

Change-Id: Ic5d84ea643161a33ed724c2576d75f4171413386
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2225680
Commit-Queue: Johann Koenig <johannkoenig@google.com>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Auto-Submit: Johann Koenig <johannkoenig@google.com>
Reviewed-by: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#774027}

third_party/blink/renderer/modules/cookie_store/cookie_store_manager.h

@@ -30,6 +30,7 @@ class CookieStoreManager final : public ScriptWrappable {
       ServiceWorkerRegistration* registration,
       HeapMojoRemote<mojom::blink::CookieStore,
                      HeapMojoWrapperMode::kWithoutContextObserver> backend);
+  ~CookieStoreManager() override = default;
 
   ScriptPromise subscribe(
       ScriptState* script_state,