When using a Views-hosted browser window the client receives Views-related
callbacks for popups and can thereby customize the Views-hosted popup behavior.
When using an external parent window no Views-related callbacks are delivered
and customization options are restricted to providing a new parent handle via
OnBeforePopup. Consequently, we should default to a normal browser window in
the external parent case instead of the very minimial Views-hosted default.
To test (A):
1. Run `cefclient --use-default-popup --enable-chrome-runtime --use-native`
2. Select Tests > Popup Window
3. Get a normal Chrome browser window
To test (B):
1. Run `cefclient --use-default-popup [--enable-chrome-runtime] [--use-views]`
2. Select Tests > Popup Window
3. Get a native or Views-hosted browser window with title bar only
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