Fix double delete in url_loader_impl.cc

R=ppi@chromium.org

Review URL: https://codereview.chromium.org/1236333003 .
diff --git a/mojo/services/network/url_loader_impl.cc b/mojo/services/network/url_loader_impl.cc
index bda30e5..955a49c 100644
--- a/mojo/services/network/url_loader_impl.cc
+++ b/mojo/services/network/url_loader_impl.cc
@@ -268,7 +268,7 @@
       current_fetcher_id_(0),
       binding_(this, request.Pass()) {
   for (auto& interceptor : interceptors_) {
-    interceptor.set_connection_error_handler([this]() { OnConnectionError(); });
+    interceptor.set_connection_error_handler([this]() { delete this; });
   }
   interceptor_index_ = interceptors_.size() - 1;
   binding_.set_connection_error_handler([this]() { OnConnectionError(); });