Fix headless_browsertests failures with PlzNavigate.

content/browser/devtools/protocol/network_handler.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/devtools/protocol/network_handler.h"
 
 #include <stddef.h>
 
 #include "base/barrier_closure.h"
 #include "base/command_line.h"
@@ skipping 653 matching lines @@
                         static_cast<double>(base::Time::kMicrosecondsPerSecond),
         Page::ResourceTypeEnum::Other, "Navigation Preload Error",
         completion_status.error_code == net::Error::ERR_ABORTED);
   }
   frontend_->LoadingFinished(
       request_id, base::TimeTicks::Now().ToInternalValue() /
                       static_cast<double>(base::Time::kMicrosecondsPerSecond),
       completion_status.encoded_data_length);
 }
 
+void NetworkHandler::NavigationFailed(const std::string& request_id,
+                                      const std::string& error_string,
+                                      bool cancelled) {
+  if (!enabled_)
+    return;
+  frontend_->LoadingFailed(

[dgozman, 2017/02/27 17:31:31]

We should send "requestWillBeSent" before "loadingFailed" with the same request
id for protocol events to be reasonably paired.

[jam, 2017/02/27 20:47:35]

Done.

+      request_id,
+      base::TimeTicks::Now().ToInternalValue() /
+          static_cast<double>(base::Time::kMicrosecondsPerSecond),
+      Page::ResourceTypeEnum::Document, error_string, cancelled);
+}
+
 std::string NetworkHandler::UserAgentOverride() const {
   return enabled_ ? user_agent_ : std::string();
 }
 
 }  // namespace protocol
 }  // namespace content