If specified, the expression is evaluated on the iframe whose URL matches
the one specified. By default, the expression is evaluated in the top
frame of the inspected page.
Evaluate the expression in the context of a content script of an extension
that matches the specified origin. If given, scriptExecutionContext
overrides the 'true' setting on useContentScriptContext.
Evaluate the expression in the context of the content script of the
calling extension, provided that the content script is already injected
into the inspected page. If not, the expression is not evaluated and the
callback is invoked with the exception parameter set to an object that has
the isError field set to true and the code field set to E_NOTFOUND.