Remove reset of SkTileGrid in PictureRenderer::init

r7885 (https://codereview.appspot.com/7350050) saw a huge regression in bench_pictures rendering time. It appears that the resetting of the SkTileGrid in PictureRenderer::init was clearing out the read-in tile size and replacing it with 1,1. When the bbh was then created we were getting a grid tile for each pixel. This patch removes the reset (the values are initialized in the ctor after all) and restores bench_picture's performance to pre-7885 levels:


7884
bench_pictures.exe ..\..\skp --mode record --bbh grid 256 256 --repeat 20
running bench [1257 2394] desk_amazon.skp   record_grid: cmsecs = 0.7800
running bench [1257 1423] desk_baidu.skp   record_grid: cmsecs = 0.7800
running bench [1257 11809] desk_blogger.skp   record_grid: cmsecs = 0.7800
running bench [1257 3045] desk_booking.skp   record_grid: cmsecs = 0.7800
running bench [1257 6612] desk_br337.skp   record_grid: cmsecs = 0.7800

7885
bench_pictures.exe ..\..\skp --mode record --bbh grid 256 256 --repeat 20
running bench [1257 2394] desk_amazon.skp   record_grid: cmsecs = 520.2633
running bench [1257 1423] desk_baidu.skp   record_grid: cmsecs = 297.1819
running bench [1257 11809] desk_blogger.skp   record_grid: cmsecs = 2954.6589
running bench [1257 3045] desk_booking.skp   record_grid: cmsecs = 731.6447
running bench [1257 6612] desk_br337.skp   record_grid: cmsecs = 1633.3305

ToT (8039)
bench_pictures.exe -r ..\..\skp --mode record --bbh grid 256 256 --repeat 20
running bench [1257 2394] desk_amazon.skp   record_grid: cmsecs = 511.6833
running bench [1257 1423] desk_baidu.skp   record_grid: cmsecs = 293.2819
running bench [1257 11809] desk_blogger.skp   record_grid: cmsecs = 3025.6394
running bench [1257 3045] desk_booking.skp   record_grid: cmsecs = 726.9647
running bench [1257 6612] desk_br337.skp   record_grid: cmsecs = 1620.8504

ToT with this patch
bench_pictures.exe -r ..\..\skp --mode record --bbh grid 256 256 --repeat 20
running bench [1257 2394] desk_amazon.skp   record_grid: cmsecs = 0.7800
running bench [1257 1423] desk_baidu.skp   record_grid: cmsecs = 0.7800
running bench [1257 11809] desk_blogger.skp   record_grid: cmsecs = 0.7800
running bench [1257 3045] desk_booking.skp   record_grid: cmsecs = 0.7800
running bench [1257 6612] desk_br337.skp   record_grid: cmsecs = 0.7800

[junov1, 2013-03-08 16:25:46]

On 2013/03/08 15:56:26, robertphillips wrote:

lgtm

I had a bug logged for this:
https://code.google.com/p/skia/issues/detail?id=1151

[robertphillips, 2013-03-08 16:27:38]

committed as r8042