Fix content scaling bug on Mac

Fix content scaling bug on Mac

The root cause was that ImageTransportSurfaceFBO was using the pixel
size of the surface to early-out of surface reallocation. This is a problem
when scale factor changed and pixel size doesn't -- the change in scale
factor is never propagated to the underlying CALayer.

Move all logic for changing the size of the surface and for skipping
changes in the size of the surface to AllocateOrResizeFramebuffer.

Rename ambiguous sizes to be labeled as pixel_size or dip_size.

Remove a stray ScopedCAActionDisabler that does nothing (found by
inspection of nearby code).

Add myself as an OWNER for this path.

BUG=424713
Committed: https://crrev.com/712fa19c0fd1757fe041280086bf01f2e5ee3793
Cr-Commit-Position: refs/heads/master@{#302363}

[ccameron, 2014-10-31 21:49:16]

ccameron@chromium.org changed reviewers:
+ kbr@chromium.org

[ccameron, 2014-10-31 21:49:59]

Simple fix.

[Ken Russell (switch to Gerrit), 2014-10-31 23:14:09]

LGTM, especially your ownership.

[ccameron, 2014-10-31 23:31:29]

Thanks!

[ccameron, 2014-10-31 23:31:34]

The CQ bit was checked by ccameron@chromium.org

[commit-bot: I haz the power, 2014-10-31 23:32:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/696823002/1

[commit-bot: I haz the power, 2014-11-01 00:14:53]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-01 00:15:17]

Patchset 1 (id:??) landed as
https://crrev.com/712fa19c0fd1757fe041280086bf01f2e5ee3793
Cr-Commit-Position: refs/heads/master@{#302363}