Create a new window. Gecko will/may call this method, if made
available to it, to create new windows.
| parent | Parent window, if any. Null if not. The newly created window should be made a child/dependent window of the parent, if any (and if the concept applies to the underlying OS). |
| chromeFlags | Chrome features from nsIWebBrowserChrome |
| contextFlags | Flags about the context of the window being created. |
| uri | The URL for which this window is intended. It can be null or zero-length. The implementation of this interface may use the URL to help determine what sort of window to open or whether to cancel window creation. It will not load the URL. |
| aOpeningTab | The TabParent that is trying to open this new chrome window. Can be nullptr. |
| cancel | Return |true| to reject window creation. If true the implementation has determined the window should not be created at all. The caller should not default to any possible backup scheme for creating the window. |
| the new window. Will be null if canceled or an error occurred. |
Definitions for contextFlags