### 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
#elif defined(OS_WIN)
#include "net/ssl/client_cert_store_win.h"
#elif defined(OS_MACOSX)
#include "net/ssl/client_cert_store_mac.h"
#include "services/audio/public/mojom/constants.mojom.h"
#elif defined(USE_OPENSSL)
#include "net/ssl/client_cert_store.h"
#endif
#if BUILDFLAG(ENABLE_PEPPER_FLASH)
#include "chrome/browser/renderer_host/pepper/chrome_browser_pepper_host_factory.h"
#endif  
#if BUILDFLAG(OVERRIDE_LOCATION_PROVIDER)
#include "shell/browser/fake_location_provider.h"
#endif  
#if BUILDFLAG(ENABLE_TTS)
#include "chrome/browser/speech/tts_controller_delegate_impl.h"
#include "chrome/browser/speech/tts_message_filter.h"
#endif  
#if BUILDFLAG(ENABLE_PRINTING)
#include "chrome/browser/printing/printing_message_filter.h"
#endif  
#if defined(OS_MACOSX)
#include "content/common/mac_helpers.h"
#include "content/public/common/child_process_host.h"
#endif
using content::BrowserThread;
namespace electron {
namespace {
bool g_suppress_renderer_process_restart = false;
bool IsSameWebSite(content::BrowserContext* browser_context,