* Output of `node_modules/.bin/electron --version`: v4.0.0
* Operating System (Platform and Version): macOS 10.14.2

* Output of `node_modules/.bin/electron --version` on last known working Electron version (if applicable): 2.0.7

### Expected behavior

I should be able to call `app.setAccessibilitySupportEnabled(true)` during initialization, and the application should start and stay open.

### Actual behavior

The application starts and exits immediately if `app.setAccessibilitySupportEnabled(true)` is called during initialization. Same for passing in `false`.

### How to reproduce

Here is a simple project that shows this error. The application behaves as expected (does not exit immediately) when this line is commented out:
https://github.com/marisademeglio/electron4-setA11yTreeEnabled/blob/master/src/main/main.js#L27

  $ git clone https://github.com/marisademeglio/electron4-setA11yTreeEnabled.git
  $ yarn install
  $ yarn start

atom/browser/api/atom_api_app.cc
v8::Local<v8::Value> val,
                     content::CertificateRequestResultType* out) {
    bool b;
    if (!ConvertFromV8(isolate, val, &b))
      return false;
    *out = b ? content::CERTIFICATE_REQUEST_RESULT_TYPE_CONTINUE
             : content::CERTIFICATE_REQUEST_RESULT_TYPE_CANCEL;
    return true;
  }
};
}  
namespace atom {
ProcessMetric::ProcessMetric(int type,
                             base::ProcessId pid,
                             std::unique_ptr<base::ProcessMetrics> metrics) {
  this->type = type;
  this->pid = pid;
  this->metrics = std::move(metrics);
}
ProcessMetric::~ProcessMetric() = default;
namespace api {
namespace {
class AppIdProcessIterator : public base::ProcessIterator {