||Asynchronously captures a thumbnail of the given URL.
The page is loaded anonymously, and plug-ins are disabled.
@param url The URL to capture.
@param options An optional object that configures the capture. Its
properties are the following, and all are optional:
@opt onDone A function that will be asynchronously called when the
capture is complete or times out. It's called as
where `url` is the captured URL.
@opt timeout The capture will time out after this many milliseconds have
elapsed after the capture has progressed to the head of
the queue and started. Defaults to 30000 (30 seconds).
@opt isImage If true, backgroundPageThumbsContent will attempt to render
the url directly to canvas. Note that images will mostly get
detected and rendered as such anyway, but this will ensure it.
@opt targetWidth The target width when capturing an image.
@opt backgroundColor The background colour when capturing an image.
||Common thumbnailing routines used by various consumers, including
PageThumbs and BackgroundPageThumbs.
||Name of the directory in the profile that contains the thumbnails.
||A service which returns information about file paths where the
screenshots for URLs are stored. These screenshots are used by the