### 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.cc
user_agent_override_ = user_agent;
}
void AtomBrowserClient::RegisterNonNetworkNavigationURLLoaderFactories(
    int frame_tree_node_id,
    NonNetworkURLLoaderFactoryMap* factories) {
  content::WebContents* web_contents =
      content::WebContents::FromFrameTreeNodeId(frame_tree_node_id);
  api::ProtocolNS* protocol = api::ProtocolNS::FromWrappedClass(
      v8::Isolate::GetCurrent(), web_contents->GetBrowserContext());
  if (protocol)
    protocol->RegisterURLLoaderFactories(factories);
}
void AtomBrowserClient::RegisterNonNetworkSubresourceURLLoaderFactories(
    int render_process_id,
    int render_frame_id,
    NonNetworkURLLoaderFactoryMap* factories) {
  
  content::RenderFrameHost* frame_host =
      content::RenderFrameHost::FromID(render_process_id, render_frame_id);
  content::WebContents* web_contents =
      content::WebContents::FromRenderFrameHost(frame_host);
  if (web_contents) {
    api::ProtocolNS* protocol = api::ProtocolNS::FromWrappedClass(
        v8::Isolate::GetCurrent(), web_contents->GetBrowserContext());
    if (protocol)
      protocol->RegisterURLLoaderFactories(factories);
  }
}
bool AtomBrowserClient::WillCreateURLLoaderFactory(