Revert "Store callback in DhcpPacFileFetcherChromeos."

This reverts commit 130902aa,
reviewed at https://crrev.com/c/1073192, and also adds
a comment that the expectation of DhcpPacFileFetcher::Fetch is violated.

Bug: 882996
Change-Id: I127d582dd0fa4a68942c2a005bd543ad8efbd161
Reviewed-on: https://chromium-review.googlesource.com/1230442
Commit-Queue: Bence Béky <bnc@chromium.org>
Reviewed-by: Steven Bennetts <stevenjb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592057}

chromeos/network/dhcp_pac_file_fetcher_chromeos.cc

@@ -4,6 +4,7 @@
 
 #include "chromeos/network/dhcp_pac_file_fetcher_chromeos.h"
 
+#include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/task_runner_util.h"
 #include "chromeos/network/network_event_log.h"
@@ -50,15 +51,12 @@ int DhcpPacFileFetcherChromeos::Fetch(
   if (!network_handler_task_runner_.get())
     return net::ERR_PAC_NOT_IN_DHCP;
   CHECK(callback);
-  // DhcpPacFileFetcher only allows one Fetch in progress at a time.
-  CHECK(!callback_);
-  callback_ = std::move(callback);
   base::PostTaskAndReplyWithResult(
       network_handler_task_runner_.get(), FROM_HERE,
       base::BindOnce(&GetPacUrlFromDefaultNetwork),
       base::BindOnce(&DhcpPacFileFetcherChromeos::ContinueFetch,
                      weak_ptr_factory_.GetWeakPtr(), utf16_text,
-                     traffic_annotation));
+                     std::move(callback), traffic_annotation));
   return net::ERR_IO_PENDING;
 }
 
@@ -82,26 +80,22 @@ std::string DhcpPacFileFetcherChromeos::GetFetcherName() const {
 
 void DhcpPacFileFetcherChromeos::ContinueFetch(
     base::string16* utf16_text,
+    net::CompletionOnceCallback callback,
     const net::NetworkTrafficAnnotationTag traffic_annotation,
     std::string pac_url) {
   NET_LOG_EVENT("DhcpPacFileFetcher", pac_url);
   pac_url_ = GURL(pac_url);
   if (pac_url_.is_empty()) {
-    std::move(callback_).Run(net::ERR_PAC_NOT_IN_DHCP);
+    std::move(callback).Run(net::ERR_PAC_NOT_IN_DHCP);
     return;
   }
 
-  int result = pac_file_fetcher_->Fetch(
-      pac_url_, utf16_text,
-      base::BindOnce(&DhcpPacFileFetcherChromeos::OnFetchCompleted,
-                     weak_ptr_factory_.GetWeakPtr()),
+  auto repeating_callback =
+      base::AdaptCallbackForRepeating(std::move(callback));
+  int res = pac_file_fetcher_->Fetch(pac_url_, utf16_text, repeating_callback,
                                      traffic_annotation);
-  if (result != net::ERR_IO_PENDING)
-    std::move(callback_).Run(result);
-}
-
-void DhcpPacFileFetcherChromeos::OnFetchCompleted(int result) {
-  std::move(callback_).Run(result);
+  if (res != net::ERR_IO_PENDING)
+    repeating_callback.Run(res);
 }
 
 }  // namespace chromeos

chromeos/network/dhcp_pac_file_fetcher_chromeos.h

@@ -38,7 +38,11 @@ class CHROMEOS_EXPORT DhcpPacFileFetcherChromeos
       net::URLRequestContext* url_request_context);
   ~DhcpPacFileFetcherChromeos() override;
 
-  // net::DhcpPacFileFetcher
+  // net::DhcpPacFileFetcher implementation
+
+  // TODO(https://crbug.com/882996)  Even though it is documented at
+  // DhcpPacFileFetcher::Fetch() that only one fetch is allowed to be
+  // outstanding at any given time, crashes show that this is not obeyed.
   int Fetch(base::string16* utf16_text,
             net::CompletionOnceCallback callback,
             const net::NetLogWithSource& net_log,
@@ -50,12 +54,10 @@ class CHROMEOS_EXPORT DhcpPacFileFetcherChromeos
 
  private:
   void ContinueFetch(base::string16* utf16_text,
+                     net::CompletionOnceCallback callback,
                      const net::NetworkTrafficAnnotationTag traffic_annotation,
                      std::string pac_url);
 
-  void OnFetchCompleted(int result);
-
-  net::CompletionOnceCallback callback_;
   std::unique_ptr<net::PacFileFetcher> pac_file_fetcher_;
   scoped_refptr<base::SingleThreadTaskRunner> network_handler_task_runner_;