DevTools: back-end for paint profiler

This adds GraphicsContextRecorder that provides a GraphicsContext that records
the canvas calls with the help of SkPicture and can then replay recordings while
timing callbacks.

BUG=135445

Review URL: https://codereview.chromium.org/104513003

git-svn-id: svn://svn.chromium.org/blink/trunk@163551 bbb929c8-8fbe-4397-9dbb-9b2b20218538