skia: Simplify SSE2 logic a bit.

skia: Simplify SSE2 logic a bit.

Chrome builds with -msse2 globally these days, so remove the skia_chrome_opts
target and fold it into skia_chrome.  Keep skia_opts but simplify the
comments there a bit.

No intended behavior change.

BUG=496512, 348761
Committed: https://crrev.com/1281ac7b9bdc8979652725a57474f82d9e1145fe
Cr-Commit-Position: refs/heads/master@{#333129}

[Nico, 2015-06-05 19:09:26]

thakis@chromium.org changed reviewers:
+ brettw@chromium.org

[brettw, 2015-06-05 19:36:13]

lgtm

[Nico, 2015-06-05 19:41:46]

The CQ bit was checked by thakis@chromium.org

[Nico, 2015-06-05 19:41:46]

The patchset sent to the CQ was uploaded after l-g-t-m from brettw@chromium.org
Link to the patchset: https://codereview.chromium.org/1161853008/#ps40001
(title: "ios")

[commit-bot: I haz the power, 2015-06-05 19:42:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1161853008/40001

[commit-bot: I haz the power, 2015-06-05 20:57:39]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-06-05 20:59:39]

Patchset 3 (id:??) landed as
https://crrev.com/1281ac7b9bdc8979652725a57474f82d9e1145fe
Cr-Commit-Position: refs/heads/master@{#333129}