- Electron version: 0.37.6
- Operating system: Windows 10

In VSCode, in order to support screen readers while editing text, we set the contents of a `<textarea>` to the contents of the line and lines surrounding the cursor and we mirror the editor selection in the `<textarea>` via `setSelectionRange`.

Chromium is not the fastest when it comes to setting large amounts of text :) (such as > 10,000 characters) and basically stalls all the time. Apparently, Electron already has some knowledge about when a screen reader is attached to the main process window (in C++ code). Is it possible to expose this as a getter + event when it first happens in the `electron` API.

We could then maintain this costly `<textarea>` sync only when really needed.

atom/browser/browser.cc
FOR_EACH_OBSERVER(BrowserObserver, observers_, OnWillFinishLaunching());
}
void Browser::DidFinishLaunching() {
  
  base::FilePath user_data;
  if (PathService::Get(brightray::DIR_USER_DATA, &user_data))
    base::CreateDirectoryAndGetError(user_data, nullptr);
  is_ready_ = true;
  FOR_EACH_OBSERVER(BrowserObserver, observers_, OnFinishLaunching());
}
void Browser::RequestLogin(
    LoginHandler* login_handler,
    std::unique_ptr<base::DictionaryValue> request_details) {
  FOR_EACH_OBSERVER(BrowserObserver,
                    observers_,
                    OnLogin(login_handler, *(request_details.get())));
}
void Browser::NotifyAndShutdown() {
  if (is_shutdown_)
    return;
  bool prevent_default = false;
  FOR_EACH_OBSERVER(BrowserObserver, observers_, OnWillQuit(&prevent_default));
  if (prevent_default) {
    is_quiting_ = false;
    return;
  }
  Shutdown();
}
bool Browser::HandleBeforeQuit() {