Use a tilegrid for bench_playback.

Use a tilegrid for bench_playback.

Using --tile wasn't a fair comparison: SkPicture didn't get to optimize its
playback, but SkRecord did.  Numbers here are starting to agree with what I saw
in telemetry: SkRecord with culling is on average at 0.8-0.9 of the speed of
SkPicture (10-30% slower) than SkPicture SkPicture with a tile grid, but some
in some cases it's down at 0.3, taking almost 4x as long to draw a 256x256 tile.

0.4x tabl_mercurynews.skp 0.109889 0.252483
0.5x tabl_cnet.skp 0.250367 0.527789
1.0x desk_mapsvg.skp 1.48698 1.49939
1.2x desk_yahoogames.skp 0.07745 0.065343
0.9x tabl_mlb.skp 0.294509 0.312505
0.8x tabl_hsfi.skp 0.250678 0.316337
0.6x tabl_worldjournal.skp 0.510204 0.828798
0.7x desk_facebook.skp 0.318981 0.483744
0.9x desk_googlehome.skp 0.06983 0.078964
0.9x desk_tigersvg.skp 0.019232 0.022611
1.0x desk_youtubetvvideo.skp 0.401614 0.401862
1.1x desk_amazon.skp 0.415552 0.362111
0.7x desk_yahooanswers.skp 0.237995 0.358659
0.7x desk_twitter.skp 0.323466 0.439772
1.2x desk_fontwipe.skp 0.121577 0.097845
1.1x desk_css3gradients.skp 0.395335 0.362087
0.9x desk_googlespreadsheet.skp 0.362056 0.406688
1.0x tabl_frantzen.skp 15.2475 14.8521
0.6x desk_forecastio.skp 0.154236 0.276881
0.7x desk_pinterest.skp 0.077433 0.11324
0.5x tabl_cuteoverload.skp 0.173014 0.361815
0.5x tabl_androidpolice.skp 0.225903 0.465608
0.6x tabl_vnexpress.skp 0.151075 0.241104
0.6x tabl_nytimes.skp 0.06515 0.117229
0.8x desk_ebay.skp 0.353437 0.422586
0.8x tabl_deviantart.skp 0.223103 0.295496
1.1x tabl_culturalsolutions.skp 0.551348 0.506104
0.9x mobi_wikipedia.skp 0.302603 0.337292
0.6x desk_linkedin.skp 0.165102 0.276149
0.6x tabl_digg.skp 0.159074 0.281529
1.2x desk_oldinboxapp.skp 0.019815 0.017146
1.0x tabl_nofolo.skp 5.18914 5.42784
0.6x desk_jsfiddlehumperclip.skp 0.076869 0.133665
1.0x desk_blogger.skp 0.206702 0.19688
0.8x desk_espn.skp 0.346386 0.451871
1.0x desk_samoasvg.skp 3.60037 3.43147
0.8x desk_booking.skp 0.338818 0.438267
1.3x desk_yahoosports.skp 0.603811 0.470052
0.6x tabl_engadget.skp 0.248995 0.404372
0.7x desk_wowwiki.skp 0.325801 0.479559
0.8x tabl_ukwsj.skp 0.326985 0.405971
0.9x tabl_gmail.skp 0.2604 0.276744
0.9x desk_googleplus.skp 8.08874 8.71105
1.1x tabl_slashdot.skp 0.559332 0.524313
0.9x desk_gmailthread.skp 0.671569 0.74134
0.8x desk_weather.skp 0.194162 0.247681
1.3x desk_rectangletransition.skp 0.218372 0.173685
0.6x tabl_gamedeksiam.skp 0.243374 0.4134
0.9x desk_jsfiddlebigcar.skp 0.162282 0.186035
0.3x desk_pokemonwiki.skp 0.202878 0.778934
0.7x tabl_googleblog.skp 0.141203 0.209971
0.8x desk_sfgate.skp 0.229078 0.275248
1.0x desk_chalkboard.skp 2.28916 2.20101
0.9x tabl_googlecalendar.skp 0.687155 0.75413
1.1x tabl_gspro.skp 0.186399 0.169522
0.5x desk_googlespreadsheetdashed.skp 0.512622 1.02815
0.6x desk_mobilenews.skp 0.183506 0.293929
0.8x tabl_techmeme.skp 0.193074 0.229106
1.2x desk_carsvg.skp 5.33047 4.34058
0.5x desk_youtube.skp 0.132663 0.248236
0.7x tabl_pravda.skp 0.21644 0.308788
1.1x desk_gws.skp 0.698107 0.625371
0.5x tabl_mozilla.skp 0.189638 0.386801
1.0x desk_baidu.skp 0.353438 0.355965
1.1x tabl_sahadan.skp 0.476226 0.416737
summary: ≥0.3x (A 0.9x, G 0.8x) ≤1.3x

Whole SKP playback speed is fine of course.

BUG=skia:2378
Committed: http://code.google.com/p/skia/source/detail?r=14673

[mtklein, 2014-05-09 14:51:41]

lgtm

[commit-bot: I haz the power, 2014-05-09 14:52:18]

CQ is trying da patch. Follow status at
 https://skia-tree-status.appspot.com/cq/mtklein@chromium.org/277653002/1

[commit-bot: I haz the power, 2014-05-09 15:00:16]

Change committed as 14673