Make remote CALayers work with browser compositor on Mac

This adds the equivalent remote layer code from RenderWidgetHostViewMac
over to the BrowserCompositorViewMac.

This code still isn't activated yet -- backpressure is still not appropriately
applied via ImageTransportLayer.

BUG=312462

Review URL: https://codereview.chromium.org/441743003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287502 0039d316-1c4b-4281-b951-d872f2087c98
3 files changed