Remove unused WeakPtrFactory from ResourceFetcher

Bug: N/A
Change-Id: Ibc805fa1831ea7dd57a00abba52824a3f09d4d01
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4190423
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Reviewed-by: Yoav Weiss <yoavweiss@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1098450}

third_party/blink/renderer/platform/loader/fetch/resource_fetcher.h

@@ -556,9 +556,6 @@ class PLATFORM_EXPORT ResourceFetcher
   // The number of sub resource loads that a service worker fetch handler
   // called respondWith. i.e. no fallback to network.
   uint32_t number_of_subresource_loads_handled_by_service_worker_ = 0;
-
-  // NOTE: This must be the last member.
-  base::WeakPtrFactory<ResourceFetcher> weak_ptr_factory_{this};
 };
 
 class ResourceCacheValidationSuppressor {