SignedExchange: If outer response was cached, plumb the info to inner response.

Bug: 863305
Change-Id: Id6d4a4fe4fce240972af183b3b5d2921cff4e51b
Reviewed-on: https://chromium-review.googlesource.com/c/1350442Reviewed-by: Kunihiko Sakamoto <ksakamoto@chromium.org>
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Tsuyoshi Horo <horo@chromium.org>
Commit-Queue: Kouhei Ueno <kouhei@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610786}

content/browser/web_package/signed_exchange_loader.cc

@@ -347,6 +347,8 @@ void SignedExchangeLoader::OnHTTPExchangeFound(
         network::mojom::kURLLoadOptionSendSSLInfoWithResponse)) {
     inner_response_head_shown_to_client.ssl_info = base::nullopt;
   }
+  inner_response_head_shown_to_client.was_fetched_via_cache =
+      outer_response_.was_fetched_via_cache;
   client_->OnReceiveResponse(inner_response_head_shown_to_client);
 
   // Currently we always assume that we have body.