Set OS X widget bitmaps immutable, and while we're here use setMatrix().

Set OS X widget bitmaps immutable, and while we're here use setMatrix().

I've been playing around with a build of Chrome that asserts all bitmaps
recorded into pictures are immutable.  Most are, but this one popped out
on sites that use native widgets (checkboxes, text fields, etc.).

While we're here, we can just call SkCanvas::setMatrix() instead of
concating the matrix with its inverse.  That works fine with SkPicture now.

BUG=

Committed: https://crrev.com/e15a3024c393bc935ec004f9a5368312c08c1465
Cr-Commit-Position: refs/heads/master@{#308088}

[mtklein, 2014-12-11 22:04:10]

mtklein@google.com changed reviewers:
+ mtklein@google.com, reed@google.com

[reed1, 2014-12-11 22:17:10]

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

[mtklein, 2014-12-12 02:01:30]

mtklein@google.com changed reviewers:
+ mtklein@google.com, reed@google.com

[mtklein, 2014-12-12 02:01:31]

Try again Mike?

(CQ if you're feeling feisty.)

[reed1, 2014-12-12 13:54:18]

lgtm

[mtklein, 2014-12-12 14:28:43]

The CQ bit was checked by mtklein@google.com

[commit-bot: I haz the power, 2014-12-12 14:29:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/801553002/1

[commit-bot: I haz the power, 2014-12-12 15:24:05]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-12-12 15:24:51]

Patchset 1 (id:??) landed as
https://crrev.com/e15a3024c393bc935ec004f9a5368312c08c1465
Cr-Commit-Position: refs/heads/master@{#308088}