Set default values in WebFetchClientSettingsObject

To avoid using uninitialized values in unittests.

Bug: 1013381
Change-Id: I27e24af750b61998f3de61634564addf42b8bcb8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1854106Reviewed-by: Matt Falkenhagen <falken@chromium.org>
Commit-Queue: Kenichi Ishibashi <bashi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704927}

third_party/blink/public/platform/web_fetch_client_settings_object.h

@@ -21,9 +21,11 @@ namespace blink {
 // Onion Soup is done.
 // Keep this struct consistent with mojom::FetchClientSettingsObject.
 struct WebFetchClientSettingsObject {
-  network::mojom::ReferrerPolicy referrer_policy;
+  network::mojom::ReferrerPolicy referrer_policy =
+      network::mojom::ReferrerPolicy::kDefault;
   WebURL outgoing_referrer;
-  mojom::InsecureRequestsPolicy insecure_requests_policy;
+  mojom::InsecureRequestsPolicy insecure_requests_policy =
+      blink::mojom::InsecureRequestsPolicy::kDoNotUpgrade;
 
   WebFetchClientSettingsObject() {}