DevtoolsUrlLoaderInterceptor: Instrument for bug 882661.

In bug 882661: one mojo::URLLoader is sending OnStartLoadingResponseBody
without sending OnReceiveResponse before.

Add instrumentation to check this never happen with this class.

Bug: 882661
Change-Id: I8a157949feacfe65f0ea1aa8c32b28352d6d6f57
Reviewed-on: https://chromium-review.googlesource.com/c/1288595
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#601087}

content/browser/devtools/devtools_url_loader_interceptor.cc

@@ -317,6 +317,9 @@ class InterceptionJob : public network::mojom::URLLoaderClient,
       pending_auth_callback_;
   TakeResponseBodyPipeCallback pending_response_body_pipe_callback_;
 
+  // TODO(https://crbug.com/882661): Remove this as soon as the bug is fixed.
+  bool on_receive_response_sent_ = false;
+
   base::WeakPtrFactory<InterceptionJob> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InterceptionJob);
@@ -889,6 +892,7 @@ Response InterceptionJob::InnerContinueRequest(
     DCHECK_EQ(State::kResponseReceived, state_);
     DCHECK(!body_reader_);
     client_->OnReceiveResponse(response_metadata_->head);
+    on_receive_response_sent_ = true;
     response_metadata_.reset();
     loader_->ResumeReadingBodyFromNet();
     client_binding_.ResumeIncomingMethodCallProcessing();
@@ -1091,6 +1095,7 @@ void InterceptionJob::ProcessRedirectByClient(const GURL& redirect_url) {
 
 void InterceptionJob::SendResponse(const base::StringPiece& body) {
   client_->OnReceiveResponse(response_metadata_->head);
+  on_receive_response_sent_ = true;
 
   // We shouldn't be able to transfer a string that big over the protocol,
   // but just in case...
@@ -1105,6 +1110,7 @@ void InterceptionJob::SendResponse(const base::StringPiece& body) {
 
   if (!response_metadata_->cached_metadata.empty())
     client_->OnReceiveCachedMetadata(response_metadata_->cached_metadata);
+  CHECK(on_receive_response_sent_);
   client_->OnStartLoadingResponseBody(std::move(pipe.consumer_handle));
   if (response_metadata_->transfer_size)
     client_->OnTransferSizeUpdated(response_metadata_->transfer_size);
@@ -1359,6 +1365,7 @@ void InterceptionJob::OnReceiveResponse(
   DCHECK(!response_metadata_);
   if (!(stage_ & InterceptionStage::RESPONSE)) {
     client_->OnReceiveResponse(head);
+    on_receive_response_sent_ = true;
     return;
   }
   loader_->PauseReadingBodyFromNet();
@@ -1432,10 +1439,13 @@ void InterceptionJob::OnStartLoadingResponseBody(
     return;
   }
   DCHECK_EQ(State::kResponseReceived, state_);
-  if (ShouldBypassForResponse())
+  if (ShouldBypassForResponse()) {
+    // Remove this CHECK once https://crbug.com/882661 is fixed.
+    CHECK(on_receive_response_sent_);
     client_->OnStartLoadingResponseBody(std::move(body));
-  else
+  } else {
     body_reader_->StartReading(std::move(body));
+  }
 }
 
 void InterceptionJob::OnComplete(