Promise which resolves to buffer or a base64 string (depending on the value of `encoding`) with captured screenshot.
## Remarks
Options object which might have the following properties:
-`path` : The file path to save the image to. The screenshot type will be inferred from file extension. If `path` is a relative path, then it is resolved relative to [current working directory](https://nodejs.org/api/process.html#process_process_cwd). If no path is provided, the image won't be saved to the disk.
-`type` : Specify screenshot type, can be either `jpeg` or `png`. Defaults to 'png'.
-`quality` : The quality of the image, between 0-100. Not applicable to `png` images.
-`fullPage` : When true, takes a screenshot of the full scrollable page. Defaults to `false`.
-`clip` : An object which specifies clipping region of the page. Should have the following fields:<br/> - `x` : x-coordinate of top-left corner of clip area.<br/> - `y` : y-coordinate of top-left corner of clip area.<br/> - `width` : width of clipping area.<br/> - `height` : height of clipping area.
-`omitBackground` : Hides default white background and allows capturing screenshots with transparency. Defaults to `false`.
-`encoding` : The encoding of the image, can be either base64 or binary. Defaults to `binary`.
-`captureBeyondViewport` : When true, captures screenshot [beyond the viewport](https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-captureScreenshot). When false, falls back to old behaviour, and cuts the screenshot by the viewport size. Defaults to `true`.
-`fromSurface` : When true, captures screenshot [from the surface rather than the view](https://chromedevtools.github.io/devtools-protocol/tot/Page/#method-captureScreenshot). When false, works only in headful mode and ignores page viewport (but not browser window's bounds). Defaults to `true`.
NOTE: Screenshots take at least 1/6 second on OS X. See [https://crbug.com/741689](https://crbug.com/741689) for discussion.