This fixes a series of issues uncovered by the Web Platform Tests.
The most immediately noticeable symptom was that, during shutdown, PuppetWidgets
on the client side attempted to delete shadow layers that were never created on
the compositor side. The usage of BasicLayerManager in all other widgets due to
headless mode meant that the PLayerTransactionParent was never initialized with
a layer manager, and thus discarded all transaction messages it received but not
delete layer messages.
The effects of only using BasicLayerManager in headless mode also showed up in
the web platform reftests, which ended up as blank white boxes in e10s mode as
the compositor thread never received paint instructions. Switching over to
using ClientLayerManager in headless mode causes these paint instructions to be
relayed.
In order to make ClientLayerManager work under headless mode, it was necessary
to implement a HeadlessCompositorWidget and hook that up to the CompositorWidget
creation function in widget/gtk. A follow-up patch will be necessary to hook up
the same for the other supported widget platforms.
MozReview-Commit-ID: 8vB3lrxP7iX
--HG--
extra : rebase_source : 4013aa856943c983b44266c4a83436b253bc7ab1
Michael Smith