### Issue Details

* **Electron Version:**
  * 3.x, 4.x, 5.x, 6.x
* **Operating System:**
  * All
* **Last Known Working Electron version:**:
  * 2.x

### Expected Behavior
When navigations occur, a new process should be created for the navigation.

### Actual Behavior
When a navigation occurs _during_ a preloads scripts execution the same process is re-used as Chromium does not think the navigation has been committed yet.  This causes a memory leak and all native node modules to break.

### To Reproduce
Fiddle: https://gist.github.com/MarshallOfSound/c89aa0037c3da114d44aa3a2d1a0fc24

### Screenshots
![image](https://user-images.githubusercontent.com/6634592/55097842-eb45dd00-5079-11e9-99bf-d49c0d997bca.png)

As you can see here there are three navigation loads, the second and the third one actually have the same process ID (and are running in the same process)
shell/browser/atom_browser_client.h
void RegisterNonNetworkNavigationURLLoaderFactories(
      int frame_tree_node_id,
      NonNetworkURLLoaderFactoryMap* factories) override;
  void RegisterNonNetworkSubresourceURLLoaderFactories(
      int render_process_id,
      int render_frame_id,
      NonNetworkURLLoaderFactoryMap* factories) override;
  bool WillCreateURLLoaderFactory(
      content::BrowserContext* browser_context,
      content::RenderFrameHost* frame,
      int render_process_id,
      bool is_navigation,
      bool is_download,
      const url::Origin& request_initiator,
      mojo::PendingReceiver<network::mojom::URLLoaderFactory>* factory_receiver,
      network::mojom::TrustedURLLoaderHeaderClientPtrInfo* header_client,
      bool* bypass_redirect_checks) override;
  network::mojom::URLLoaderFactoryPtrInfo
  CreateURLLoaderFactoryForNetworkRequests(
      content::RenderProcessHost* process,
      network::mojom::NetworkContext* network_context,
      network::mojom::TrustedURLLoaderHeaderClientPtrInfo* header_client,
      const url::Origin& request_initiator) override;
#if defined(OS_WIN)
  bool PreSpawnRenderer(sandbox::TargetPolicy* policy) override;
#endif
  bool HandleExternalProtocol(
      const GURL& url,
      content::WebContents::Getter web_contents_getter,
      int child_id,