Refactor device scale factor on Mac and fix CoreAnimation bug

Refactor device scale factor on Mac and fix CoreAnimation bug

Rename some functions to be more meaningful:
- RWHVMac::scale_factor -> RWHVMac::ViewScaleFactor
- RWHVCocoa::deviceScaleFactor_ -> RWHVMac::backing_store_scale_factor
- ::ScaleFactor(NSView*) -> ScaleFactorForView(NSView*)

Move code to update the scale factor of the backing store from
being in RWHVCocoa::updateTabBackingStoreScaleFactor to be
in RWHVMac::UpdateBackingStoreScaleFactor.

Work around a bug where updating the contentsScale of a
CAOpenGLLayer that dynamically changes its isAsynchronous
property results in corruption by re-creating the CAOpenGLLayer
when a change in scale factor is detected.

BUG=245900
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=251982

[ccameron, 2014-02-19 00:52:05]

Mostly cleanup, and a small bugfix.

https://codereview.chromium.org/171763002/diff/30001/content/browser/renderer...
File content/browser/renderer_host/render_widget_host_view_mac.mm (left):

https://codereview.chromium.org/171763002/diff/30001/content/browser/renderer...
content/browser/renderer_host/render_widget_host_view_mac.mm:500: if
(compositing_iosurface_) {
This block was a remnant from when dynamically enabling CoreAnimation was a
thing -- this is only called during init when there is no IOSurface yet now.

[jbauman, 2014-02-19 01:51:00]

lgtm

[ccameron, 2014-02-19 01:54:19]

Thanks!

[ccameron, 2014-02-19 01:54:24]

The CQ bit was checked by ccameron@chromium.org

[commit-bot: I haz the power, 2014-02-19 01:58:13]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/ccameron@chromium.org/171763002/30001

[commit-bot: I haz the power, 2014-02-19 07:54:13]

Change committed as 251982