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### Preflight Checklist
<!-- Please ensure you've completed the following steps by replacing [ ] with [x]-->

* [x] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
* [x] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
* [x] I have searched the issue tracker for an issue that matches the one I want to file, without success.

### Issue Details

* **Electron Version:**
  * 6.0.0-beta.5, 5.0.2
* **Operating System:**
  * Linux - Ubuntu 18.04 x64
* **Last Known Working Electron version:**
  * 4.2.3

### Expected Behavior
<!-- A clear and concise description of what you expected to happen. -->
Electron should warn root users that `Running as root without --no-sandbox is not supported.`, even if ELECTRON_ENABLE_LOGGING is not set

### Actual Behavior
<!-- A clear and concise description of what actually happened. -->
Running Electron as root fails silently, unless the user sets the environment variable `ELECTRON_ENABLE_LOGGING=true`.  When `ELECTRON_ENABLE_LOGGING=true`, the console displays the message: 
```sh
Running as root without --no-sandbox is not supported.
```
This behaviour is really confusing as causes people to think Electron doesn't work on their platform (eg see #18350) We should provide more context here.

### To Reproduce
As root run:
```sh
$ git clone https://github.com/electron/electron-quick-start.git
$ npm install
$ npm start 
```
No output.

Again as root run: 
```sh
$ export ELECTRON_ENABLE_LOGGING=true
$ npm start
```
Warning message appears

### Screenshots
<!-- If applicable, add screenshots to help explain your problem. -->

### Additional Information
<!-- Add any other context about the problem here. -->

shell/app/atom_main_delegate.cc
bool AtomMainDelegate::BasicStartupComplete(int* exit_code) {
  auto* command_line = base::CommandLine::ForCurrentProcess();
  logging::LoggingSettings settings;
#if defined(OS_WIN)
#if defined(_WIN64)
  crash_reporter::CrashReporterWin::SetUnhandledExceptionFilter();
#endif
  
  
  if (IsBrowserProcess(command_line))
    std::wcout << std::endl;
#if defined(DEBUG)
  
  settings.logging_dest = logging::LOG_TO_ALL;
  base::FilePath log_filename;
  base::PathService::Get(base::DIR_EXE, &log_filename);
  log_filename = log_filename.AppendASCII("debug.log");
  settings.log_file = log_filename.value().c_str();
  settings.lock_log = logging::LOCK_LOG_FILE;
  settings.delete_old = logging::DELETE_OLD_LOG_FILE;
#else
  settings.logging_dest =
      logging::LOG_TO_SYSTEM_DEBUG_LOG | logging::LOG_TO_STDERR;
#endif  
#else   
  settings.logging_dest =
      logging::LOG_TO_SYSTEM_DEBUG_LOG | logging::LOG_TO_STDERR;
#endif  
  
  auto env = base::Environment::Create();