Implementation Details (WIP)

WebExtension

Permission	Usage
`browser.history`	When opening receiver selection popup windows, the history log is polluted unless these entries are removed.
`menus`	Display context menus for casting on pages/media, and whitelist menus on the toolbar button.
`nativeMessaging`	Allows communciation with the bridge.
`notifications`	Show notifications if a bridge issue is found on startup.
`storage`	Store options data.
`tabs`	Execute scripts within a sender application's tab content script context(possibly unnecessary due to host permissions).
`webNavigation`	Get URL of frame to determine available cast media types.
`webRequest`	Intercept and redirect Cast SDK requests.
`<all_urls>`	Wildcard host permission (may want to switch to optional host permissions).