Move more compositor backend checks into gfxPlatform. (bug 1179051 part 4, r=mattwoodrow)

--HG--
extra : rebase_source : 887ed513fc50f2c1ee560ffa4a795b5c847154fe

gfx/layers/d3d11/CompositorD3D11.cpp

@@ -135,10 +135,7 @@ CompositorD3D11::Initialize()
 
   ScopedGfxFeatureReporter reporter("D3D11 Layers", force);
 
-  if (!gfxPlatform::CanUseDirect3D11()) {
-    NS_WARNING("Direct3D 11-accelerated layers are not supported on this system.");
-    return false;
-  }
+  MOZ_ASSERT(gfxPlatform::CanUseDirect3D11());
 
   HRESULT hr;
 

gfx/layers/d3d9/CompositorD3D9.cpp

@@ -45,10 +45,7 @@ CompositorD3D9::Initialize()
 
   ScopedGfxFeatureReporter reporter("D3D9 Layers", force);
 
-  if (!gfxPlatform::CanUseDirect3D9()) {
-    NS_WARNING("Direct3D 9-accelerated layers are not supported on this system.");
-    return false;
-  }
+  MOZ_ASSERT(gfxPlatform::CanUseDirect3D9());
 
   mDeviceManager = gfxWindowsPlatform::GetPlatform()->GetD3D9DeviceManager();
   if (!mDeviceManager) {

gfx/thebes/gfxWindowsPlatform.cpp

@@ -2393,11 +2393,19 @@ gfxWindowsPlatform::GetAcceleratedCompositorBackends(nsTArray<LayersBackend>& aB
   }
 
   if (!gfxPrefs::LayersPreferD3D9()) {
-    aBackends.AppendElement(LayersBackend::LAYERS_D3D11);
+    if (gfxPlatform::CanUseDirect3D11() && GetD3D11Device()) {
+      aBackends.AppendElement(LayersBackend::LAYERS_D3D11);
+    } else {
+      NS_WARNING("Direct3D 11-accelerated layers are not supported on this system.");
+    }
   }
 
   if (gfxPrefs::LayersPreferD3D9() || !IsVistaOrLater()) {
     // We don't want D3D9 except on Windows XP
-    aBackends.AppendElement(LayersBackend::LAYERS_D3D9);
+    if (gfxPlatform::CanUseDirect3D9()) {
+      aBackends.AppendElement(LayersBackend::LAYERS_D3D9);
+    } else {
+      NS_WARNING("Direct3D 9-accelerated layers are not supported on this system.");
+    }
   }
 }