To make the HeadlessCompositorWidget work under Windows as well as Linux, I had
to change the way that I hooked it into the existing CompositorWidget system.
Under GTK, the CompositorWidgetInitData and CompositorWidgetDelegate types
provided the information needed by the headless compositor widget already (the
widget client size). On Windows, however, the definitions of these types
differ, and the client size information is simply retrieved from the platform
APIs when needed.
After this patch, CompositorWidgetDelegate is renamed to
PlatformCompositorWidgetDelegate, and a new base class called
CompositorWidgetDelegate is added with "AsPlatformSpecificDelegate()" and
"AsHeadlessCompositorWidget()" methods. In non-headless mode, widgets use
AsPlatformSpecificDelegate() to access the Windows- and GTK-specific delegate
APIs. In headless mode, AsHeadlessCompositorWidget() is used to access the
singular CompositorWidget implementation for headless. Meanwhile, the
CompositorWidgetInitData IPDL type is made into a union which always contains a
headless-specific HeadlessCompositorWidgetInitData struct and under GTK and
Windows also contains an {X11,Win}CompositorWidgetInitData struct.
This also includes a small patch to ensure that the GPU process and
hardware-accelerated compositing are always disabled under headless mode. These
features weren't activated by default in the Linux environments I tested in, but
did end up activating (and then promptly crashing Firefox) when I tested on
Windows.
MozReview-Commit-ID: CocPoHBDV7H
--HG--
extra : rebase_source : 4581fa63aa3a9f32a8dc2672015a35b9be01b20f
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