Bug 1599673 - Add webrender compositor enabled log to Decision Log in about:support r=nical,jrmuizel

FeatureState does not add a log when it is enabled by default. But we want it for Feature::WEBRENDER_COMPOSITOR.

Differential Revision: https://phabricator.services.mozilla.com/D56848

--HG--
extra : moz-landing-system : lando

gfx/thebes/gfxPlatform.cpp

@@ -3326,6 +3326,9 @@ void gfxPlatform::InitWebRenderConfig() {
 
   if (gfx::gfxConfig::IsEnabled(gfx::Feature::WEBRENDER_COMPOSITOR)) {
     gfxVars::SetUseWebRenderCompositor(true);
+    // Call UserEnable() only for reporting to Decision Log.
+    // If feature is enabled by default. It is not reported to Decision Log.
+    featureComp.UserEnable("Enabled");
   }
 
   // Set features that affect WR's RendererOptions