[chromium] Pass SkBitmap by reference in WebNinePatchLayer::setBitmap and refactor

[chromium] Pass SkBitmap by reference in WebNinePatchLayer::setBitmap and refactor

Although passing SkBitmap by value doesn't copy the underlying pixels, it indeed
involves memcpy (~64 bytes to be precise) to replicate the settings from the
other bitmap in the copy constructor.

This overhead, albeit minor, can be avoided by passing SkBitmap as reference.

R=jamesr@chromium.org

Committed: https://crrev.com/f814f45c209ebc36f28251d8de602c099a54262e
Cr-Commit-Position: refs/heads/master@{#296330}

[vivekg, 2014-09-23 14:46:37]

PTAL, thank you!

Blink side changes here: https://codereview.chromium.org/594193002

[jamesr, 2014-09-23 23:33:34]

lgtm

[vivekg, 2014-09-24 00:24:57]

The CQ bit was checked by vivekg@chromium.org

[commit-bot: I haz the power, 2014-09-24 00:26:04]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/597553002/1

[commit-bot: I haz the power, 2014-09-24 02:10:23]

Committed patchset #1 (id:1) as 94c31015dce1f3febd9ef2b44d082818f155ee03

[commit-bot: I haz the power, 2014-09-24 02:11:13]

Patchset 1 (id:??) landed as
https://crrev.com/f814f45c209ebc36f28251d8de602c099a54262e
Cr-Commit-Position: refs/heads/master@{#296330}