Provide reasons for ConnectionAttempt() failures logs

Bug: 1106937
Change-Id: Ica9e835c591950ed66312f82b55fab3e79d6b5a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2401704Reviewed-by: Kyle Horimoto <khorimoto@chromium.org>
Commit-Queue: Jimmy Gong <jimmyxgong@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805550}

chromeos/components/phonehub/connection_manager_impl.cc

@@ -85,7 +85,8 @@ void ConnectionManagerImpl::SendMessage(const std::string& payload) {
 
 void ConnectionManagerImpl::OnConnectionAttemptFailure(
     chromeos::secure_channel::mojom::ConnectionAttemptFailureReason reason) {
-  PA_LOG(WARNING) << "AttemptConnection() failed to establish connection.";
+  PA_LOG(WARNING) << "AttemptConnection() failed to establish connection with "
+                  << "error: " << reason << ".";
   connection_attempt_.reset();
   NotifyStatusChanged();
 }