Instrument WebRequestProxyingUrlLoader for bug 882661

What we know about the bug:
* URLLoaderClient::OnStartLoadingResponseBody is sent before
  URLLoaderClient::OnReceiveResponse.
* Users have one or more ad blocking extensions.
* The NetworkService is enabled.
* Websites are loading content inside an iframe that has never
  navigated. Its URL is still about:blank or javascript:*

This CL Instrument WebRequestProxyingUrlLoader. The goal is to confirm this
bug is about extensions.

Bug: 882661
Change-Id: I1ce33cdb703adb1a854c37f46cafd80a85649388
Reviewed-on: https://chromium-review.googlesource.com/c/1319710
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605730}

extensions/browser/api/web_request/web_request_proxying_url_loader_factory.cc

@@ -6,6 +6,8 @@
 
 #include <utility>
 
+#include "base/debug/alias.h"
+#include "base/debug/dump_without_crashing.h"
 #include "base/strings/stringprintf.h"
 #include "base/task/post_task.h"
 #include "content/public/browser/browser_task_traits.h"
@@ -150,6 +152,7 @@ void WebRequestProxyingURLLoaderFactory::InProgressRequest::
 void WebRequestProxyingURLLoaderFactory::InProgressRequest::OnReceiveResponse(
     const network::ResourceResponseHead& head) {
   current_response_ = head;
+  on_receive_response_received_ = true;
   HandleResponseOrRedirectHeaders(
       base::BindRepeating(&InProgressRequest::ContinueToResponseStarted,
                           weak_factory_.GetWeakPtr()));
@@ -191,6 +194,13 @@ void WebRequestProxyingURLLoaderFactory::InProgressRequest::
 
 void WebRequestProxyingURLLoaderFactory::InProgressRequest::
     OnStartLoadingResponseBody(mojo::ScopedDataPipeConsumerHandle body) {
+  // TODO(https://crbug.com/882661): Remove this once the bug is fixed.
+  if (!on_receive_response_sent_) {
+    bool on_receive_response_received = on_receive_response_received_;
+    base::debug::Alias(&on_receive_response_received);
+    DEBUG_ALIAS_FOR_GURL(request_url, request_.url)
+    base::debug::DumpWithoutCrashing();
+  }
   target_client_->OnStartLoadingResponseBody(std::move(body));
 }
 
@@ -441,6 +451,7 @@ void WebRequestProxyingURLLoaderFactory::InProgressRequest::
     // |FollowRedirect()|.
     proxied_client_binding_.Close();
     target_loader_.reset();
+    on_receive_response_received_ = false;
 
     ContinueToBeforeRedirect(redirect_info, net::OK);
     return;
@@ -452,6 +463,7 @@ void WebRequestProxyingURLLoaderFactory::InProgressRequest::
 
   ExtensionWebRequestEventRouter::GetInstance()->OnResponseStarted(
       factory_->browser_context_, factory_->info_map_, &info_.value(), net::OK);
+  on_receive_response_sent_ = true;
   target_client_->OnReceiveResponse(current_response_);
 }
 

extensions/browser/api/web_request/web_request_proxying_url_loader_factory.h

@@ -139,6 +139,10 @@ class WebRequestProxyingURLLoaderFactory
     // lifetime.
     base::Optional<net::AuthCredentials> auth_credentials_;
 
+    // TODO(https://crbug.com/882661): Remove this once the bug is fixed.
+    bool on_receive_response_received_ = false;
+    bool on_receive_response_sent_ = false;
+
     bool request_completed_ = false;
 
     base::WeakPtrFactory<InProgressRequest> weak_factory_;