Change picture record benchmark to include begin/end record in timings and make the source picture …

Change picture record benchmark to include begin/end record in timings and make the source picture draw itself into record canvas, so it records the draws instead of directly copying the picture.
Committed: https://code.google.com/p/skia/source/detail?r=5323

[rileya, 2012-08-28 19:05:02]

The current code calls drawPicture on the record canvas, which simply records a
single "drawPicture" command and copies the source picture, rather than actually
playing back all the draws into the record canvas. Calling SkPicture::draw()
from the source picture into the record canvas fixes this.

I also moved begin/end recording into the timed part of the bench, I'm not 100%
sure that this is always desirable, but for my current use case this is very
helpful (my R-Tree picture playback does most of its work in endRecording).

[reed1, 2012-08-28 19:07:30]

lgtm