Update from https://crrev.com/304121

sky/viewer/platform/weblayertreeview_impl.cc

Index: sky/viewer/platform/weblayertreeview_impl.cc
diff --git a/sky/viewer/platform/weblayertreeview_impl.cc b/sky/viewer/platform/weblayertreeview_impl.cc
index 2aa5486baa1ac095951c0aa332cc476ebeec2eb2..f718fc34c2778232dc02fa3d12925ddd1c351b24 100644
--- a/sky/viewer/platform/weblayertreeview_impl.cc
+++ b/sky/viewer/platform/weblayertreeview_impl.cc
@@ -7,6 +7,7 @@
 #include "base/message_loop/message_loop_proxy.h"
 #include "cc/layers/layer.h"
 #include "cc/output/begin_frame_args.h"
+#include "cc/scheduler/begin_frame_source.h"
 #include "cc/trees/layer_tree_host.h"
 #include "mojo/cc/context_provider_mojo.h"
 #include "mojo/cc/output_surface_mojo.h"
@@ -47,7 +48,8 @@ WebLayerTreeViewImpl::WebLayerTreeViewImpl(
                                         gpu_memory_buffer_manager,
                                         settings,
                                         base::MessageLoopProxy::current(),
-                                        compositor_message_loop_proxy);
+                                        compositor_message_loop_proxy,
+                                        nullptr);
   DCHECK(layer_tree_host_);
 }