Fix headless_browsertests failures with PlzNavigate.

content/browser/devtools/protocol/network_handler.cc

Index: content/browser/devtools/protocol/network_handler.cc
diff --git a/content/browser/devtools/protocol/network_handler.cc b/content/browser/devtools/protocol/network_handler.cc
index 013609738d34bb0c010df75e2bc86050e3b409d1..77b4d86ed3173deb89222d092cd39c522fe5ebb9 100644
--- a/content/browser/devtools/protocol/network_handler.cc
+++ b/content/browser/devtools/protocol/network_handler.cc
@@ -671,6 +671,18 @@ void NetworkHandler::NavigationPreloadCompleted(
       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();
 }