Remove unused blitting functions from ui/gfx/blit.cc

Remove unused blitting functions from ui/gfx/blit.cc

There are no remaining call sites for either BlitContextToCanvas or
BlitCanvasToContext. Also remove some leftover #includes.

TEST=Linux built compiles & links.

Committed: https://crrev.com/3f631cbe673528365f8c0d26188a4a00c942f946
Cr-Commit-Position: refs/heads/master@{#330543}

[spang, 2015-05-15 22:03:31]

spang@chromium.org changed reviewers:
+ sadrul@chromium.org

[sadrul, 2015-05-15 22:05:09]

lgtm assuming all the bots are green

[spang, 2015-05-15 23:18:24]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2015-05-15 23:21:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138753003/1

[commit-bot: I haz the power, 2015-05-15 23:32:41]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-05-15 23:32:43]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[spang, 2015-05-19 15:59:29]

spang@chromium.org changed reviewers:
+ davidben@chromium.org

[spang, 2015-05-19 15:59:30]

+davidben for content/OWNERS

[davidben, 2015-05-19 16:05:53]

lgtm

[spang, 2015-05-19 16:23:20]

The CQ bit was checked by spang@chromium.org

[commit-bot: I haz the power, 2015-05-19 16:23:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1138753003/1

[commit-bot: I haz the power, 2015-05-19 17:20:51]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-19 17:21:30]

Patchset 1 (id:??) landed as
https://crrev.com/3f631cbe673528365f8c0d26188a4a00c942f946
Cr-Commit-Position: refs/heads/master@{#330543}