Bug 1642014 - Expose HW_COMPOSITING feature to telemetry. r=aosmond

FEATURE_FAILURE_D3D11_NEED_HWCOMP is one of the main reasons
people get the basic compositor. This will let us dig into
why we get FEATURE_FAILURE_D3D11_NEED_HWCOMP.

Differential Revision: https://phabricator.services.mozilla.com/D77554

widget/GfxInfoBase.cpp

@@ -1604,6 +1604,10 @@ bool GfxInfoBase::BuildFeatureStateLog(JSContext* aCx,
 void GfxInfoBase::DescribeFeatures(JSContext* aCx, JS::Handle<JSObject*> aObj) {
   JS::Rooted<JSObject*> obj(aCx);
 
+  gfx::FeatureState& hwCompositing =
+      gfxConfig::GetFeature(gfx::Feature::HW_COMPOSITING);
+  InitFeatureObject(aCx, aObj, "hwCompositing", hwCompositing, &obj);
+
   gfx::FeatureState& gpuProcess =
       gfxConfig::GetFeature(gfx::Feature::GPU_PROCESS);
   InitFeatureObject(aCx, aObj, "gpuProcess", gpuProcess, &obj);