Rewrite snapshot profiling, logging and replaying.

Review URL: https://codereview.chromium.org/348653003

Review URL: https://codereview.chromium.org/348653003

git-svn-id: svn://svn.chromium.org/blink/trunk@177580 bbb929c8-8fbe-4397-9dbb-9b2b20218538