analysis_canvas_unittest: tilegrid -> rtree

analysis_canvas_unittest: tilegrid -> rtree

This updates analysis_canvas_unittest.cc to match the rest of Chromium,
using an SkRTree instead of an SkTileGrid.  This helps us delete SkTileGrid.

The remaining references to SkTileGridFactory are all just to
SkTileGridFactory::TileGridInfo, which I'll clean up in another pass.

BUG=skia:3085
Committed: https://crrev.com/654791af847d3d323dc898db3d6bdeb0834fb512
Cr-Commit-Position: refs/heads/master@{#310768}

[mtklein, 2015-01-08 21:15:41]

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

[robertphillips, 2015-01-09 13:24:06]

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

[robertphillips, 2015-01-09 13:24:07]

lgtm

[mtklein, 2015-01-09 13:30:48]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2015-01-09 13:31:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/841173003/1

[commit-bot: I haz the power, 2015-01-09 14:12:39]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-01-09 14:13:28]

Patchset 1 (id:??) landed as
https://crrev.com/654791af847d3d323dc898db3d6bdeb0834fb512
Cr-Commit-Position: refs/heads/master@{#310768}