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### Issue Details
Electron Version: All Version
Operating System: macOS 10.15.3
Last Known Working Electron version: Never

### Bug
The color picker in devtools does not work.
In devtools if you want to change the colors of the CSS code. When you click on a color a color picker is supposed to appear but it does not appear.

### Screenshots
<img width="1013" alt="Capture d’écran 2020-09-07 à 11 42 44" src="https://user-images.githubusercontent.com/70572698/92374841-988ea280-f100-11ea-96be-afc93f6dd645.png">

shell/browser/api/electron_api_web_contents.cc
PrintViewManagerElectron class does not do null check.
  if (!ontents()) {
    if (print_callback)
      std::move(print_callback).Run(false, "failed");
    return;
  }
  std::u16string printer_name =
      device_name.empty() ? default_printer : device_name;
   If there are no valid printers available on the network, we bail.
  if (printer_name.empty() || !IsDeviceNameValid(printer_name)) {
    if (print_callback)
      std::move(print_callback).Run(false, "no valid printers available");
    return;
  }
  print_settings.SetStringKey(printing::kSettingDeviceName, printer_name);
  auto* print_view_manager =
      PrintViewManagerElectron::FromWebContents(ontents());
  if (!print_view_manager)
    return;
  auto* focused_frame = ontents()->GetFocusedFrame();
  auto* rfh = focused_frame && focused_frame->HasSelection()
                  ? focused_frame
                  : ontents()->GetMainFrame();
  print_view_manager->PrintNow(rfh, silent, std::move(print_settings),
                               std::move(print_callback));
}
void WebContents::Print(gin::Arguments* args) {