Remove WebCompositorSupport

sky/viewer/platform/platform_impl.cc

Index: sky/viewer/platform/platform_impl.cc
diff --git a/sky/viewer/platform/platform_impl.cc b/sky/viewer/platform/platform_impl.cc
index 8e0955cab8e49e22b4f7d0720adce02471822cf4..7766292fc6d6f2b71eaffd1bcd6a05b5a26b85af 100644
--- a/sky/viewer/platform/platform_impl.cc
+++ b/sky/viewer/platform/platform_impl.cc
@@ -114,10 +114,6 @@ bool PlatformImpl::isThreadedCompositingEnabled() {
   return true;
 }
 
-blink::WebCompositorSupport* PlatformImpl::compositorSupport() {
-  return nullptr;
-}
-
 mojo::NetworkService* PlatformImpl::networkService() {
   return network_service_.get();
 }