* Electron version: 1.7.x
* Operating system: Windows

### Expected behavior
removeAsDefaultProtocolClient should also delete the protocol key - HKCU\Software\Classes\#protocol#

### Actual behavior
removeAsDefaultProtocolClient doesn't delete the protocol key - HKCU\Software\Classes\#protocol#

### How to reproduce
Call app.setAsDefaultProtocolClient('foo') and app.removeAsDefaultProtocolClient('foo'). HKCU\Software\Classes\foo stay in the registry for windows.
atom/browser/browser_win.cc
base::FilePath path;
  if (!PathService::Get(base::FILE_EXE, &path)) {
    LOG(ERROR) << "Error getting app exe path";
    return false;
  }
  *exe = path.value();
  return true;
}
bool GetProtocolLaunchPath(mate::Arguments* args, base::string16* exe) {
  if (!args->GetNext(exe) && !GetProcessExecPath(exe)) {
    return false;
  }
  
  std::vector<base::string16> launch_args;
  if (args->GetNext(&launch_args) && !launch_args.empty())
    *exe = base::StringPrintf(L"\"%ls\" %ls \"%%1\"",
                              exe->c_str(),
                              base::JoinString(launch_args, L" ").c_str());
  else
    *exe = base::StringPrintf(L"\"%ls\" \"%%1\"", exe->c_str());
  return true;
}
bool FormatCommandLineString(base::string16* exe,