Use in-class initializers for base::WeakPtrFactory in net/.

Generated by: https://chromium-review.googlesource.com/c/chromium/src/+/1689216

Bug: 981415
Change-Id: I8b3e41ce53df33f8fc201e175a65cae3a9e07669
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1691082
Reviewed-by: Eric Roman <[email protected]>
Commit-Queue: Jeremy Roman <[email protected]>
Cr-Commit-Position: refs/heads/master@{#675307}
diff --git a/net/proxy_resolution/pac_file_fetcher_impl.cc b/net/proxy_resolution/pac_file_fetcher_impl.cc
index da10413f..506eeac 100644
--- a/net/proxy_resolution/pac_file_fetcher_impl.cc
+++ b/net/proxy_resolution/pac_file_fetcher_impl.cc
@@ -335,8 +335,7 @@
       result_text_(nullptr),
       max_response_bytes_(kDefaultMaxResponseBytes),
       max_duration_(kDefaultMaxDuration),
-      allow_file_url_(allow_file_url),
-      weak_factory_(this) {
+      allow_file_url_(allow_file_url) {
   DCHECK(url_request_context);
 }