Bug 1345017 - Disable OMTA with webrender by default, r=kats

MozReview-Commit-ID: 4cA8n8XYall

gfx/layers/wr/WebRenderBridgeParent.cpp

@@ -641,16 +641,19 @@ WebRenderBridgeParent::CompositeToTarget(gfx::DrawTarget* aTarget, const gfx::In
     return;
   }
 
-  nsTArray<WrOpacityProperty> opacityArray;
-  nsTArray<WrTransformProperty> transformArray;
-  SampleAnimations(opacityArray, transformArray);
+  if (gfxPrefs::WebRenderOMTAEnabled()) {
+    nsTArray<WrOpacityProperty> opacityArray;
+    nsTArray<WrTransformProperty> transformArray;
+    SampleAnimations(opacityArray, transformArray);
 
-  if (!transformArray.IsEmpty() || !opacityArray.IsEmpty()) {
-    mApi->GenerateFrame(opacityArray, transformArray);
-    ScheduleComposition();
-  } else {
-    mApi->GenerateFrame();
+    if (!transformArray.IsEmpty() || !opacityArray.IsEmpty()) {
+      mApi->GenerateFrame(opacityArray, transformArray);
+      ScheduleComposition();
+      return;
+    }
   }
+
+  mApi->GenerateFrame();
 }
 
 void

gfx/layers/wr/WebRenderContainerLayer.cpp

@@ -37,7 +37,8 @@ WebRenderContainerLayer::RenderLayer(wr::DisplayListBuilder& aBuilder)
                   Stringify(mixBlendMode).c_str());
   }
 
-  if (GetAnimations().Length()) {
+  if (gfxPrefs::WebRenderOMTAEnabled() &&
+      GetAnimations().Length()) {
     MOZ_ASSERT(GetCompositorAnimationsId());
 
     CompositorAnimations anim;

gfx/layers/wr/WebRenderContainerLayer.h

@@ -25,7 +25,9 @@ public:
 protected:
   virtual ~WebRenderContainerLayer()
   {
-    if (GetAnimations().Length()) {
+
+    if (gfxPrefs::WebRenderOMTAEnabled() &&
+        GetAnimations().Length()) {
       mManager->AsWebRenderLayerManager()->
         AddCompositorAnimationsIdForDiscard(GetCompositorAnimationsId());
     }

gfx/thebes/gfxPrefs.h

@@ -455,6 +455,7 @@ private:
 
   DECL_GFX_PREF(Live, "gfx.vsync.collect-scroll-transforms",   CollectScrollTransforms, bool, false);
   DECL_GFX_PREF(Once, "gfx.vsync.compositor.unobserve-count",  CompositorUnobserveCount, int32_t, 10);
+  DECL_GFX_PREF(Live, "gfx.webrender.omta.enabled",            WebRenderOMTAEnabled, bool, false);
   DECL_GFX_PREF(Live, "gfx.webrender.profiler.enable",         WebRenderProfilerEnabled, bool, false);
   // Use vsync events generated by hardware
   DECL_GFX_PREF(Once, "gfx.work-around-driver-bugs",           WorkAroundDriverBugs, bool, true);