nanobench: lazily decode bitmaps from SKPs

nanobench: lazily decode bitmaps from SKPs

This makes it considerably cheaper to run SKP recording benchmarks, without
affecting their measurements and without really affecting SKP playback
benchmarks at all.

On my machine, running out/Release/nanobench --match skp --config nondrendering
drops in run time from 6.7s to 2.5s, and the peak RAM usage drops from 129M to 50M.

I'm strongly considering making this lazy decoding the default.

BUG=skia:2944
Committed: https://skia.googlesource.com/skia/+/d664c21a38de98d8db210c46f7a8c4187f1534da

[mtklein, 2014-09-16 20:17:34]

mtklein@google.com changed reviewers:
+ mtklein@google.com, robertphillips@google.com

[robertphillips, 2014-09-16 20:21:27]

lgtm

[mtklein, 2014-09-16 20:28:20]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-09-16 20:29:00]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/572933006/1

[commit-bot: I haz the power, 2014-09-16 20:36:18]

Committed patchset #1 (id:1) as d664c21a38de98d8db210c46f7a8c4187f1534da

[jcgregorio, 2014-09-17 13:09:02]

On 2014/09/16 20:36:18, I haz the power (commit-bot) wrote:
> Committed patchset #1 (id:1) as d664c21a38de98d8db210c46f7a8c4187f1534da

It does look like this CL did affect measured performance, is that expected?

http://skiaperf.com/#427
http://skiaperf.com/#428

[jcgregorio, 2014-09-17 13:13:27]

On 2014/09/17 13:09:02, jcgregorio wrote:
> On 2014/09/16 20:36:18, I haz the power (commit-bot) wrote:
> > Committed patchset #1 (id:1) as d664c21a38de98d8db210c46f7a8c4187f1534da
> 
> It does look like this CL did affect measured performance, is that expected?
> 
> http://skiaperf.com/#427
> http://skiaperf.com/#428

Filed as https://code.google.com/p/skia/issues/detail?id=2944 for discussion.

[mtklein, 2014-09-17 13:58:24]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/554583004/ by mtklein@google.com.

The reason for reverting is: skia:2944.