cc : Stop pushing layers from hidden subtrees at commit

cc/layers/surface_layer.cc

Index: cc/layers/surface_layer.cc
diff --git a/cc/layers/surface_layer.cc b/cc/layers/surface_layer.cc
index 573f97b9b13280a3c9f5806052f0c7d81e52bd74..a5d17448b80e19a4e48faae3d30764297f75fea4 100644
--- a/cc/layers/surface_layer.cc
+++ b/cc/layers/surface_layer.cc
@@ -99,11 +99,41 @@ bool SurfaceLayer::HasDrawableContent() const {
   return primary_surface_info_.is_valid() && Layer::HasDrawableContent();
 }
 
+const SurfaceId* SurfaceLayer::GetSurfaceId(LayerTreeHost* new_host) {
+  LayerTreeHost* old_host = layer_tree_host();
+  DCHECK(!old_host || !new_host ||
+         old_host->GetSettings().enable_surface_synchronization ==
+             new_host->GetSettings().enable_surface_synchronization);
+
+  bool enable_surface_synchronization;
+  if (old_host) {
+    enable_surface_synchronization =
+        old_host->GetSettings().enable_surface_synchronization;
+  } else {
+    DCHECK(new_host);
+    enable_surface_synchronization =
+        new_host->GetSettings().enable_surface_synchronization;
+  }
+
+  if (enable_surface_synchronization) {
+    if (fallback_surface_info_.is_valid())
+      return &fallback_surface_info_.id();
+  } else {
+    return &primary_surface_info_.id();
+  }
+  return nullptr;

[jaydasika, 2017/05/23 00:25:14]

Not sure if this is correct / there is a simpler way to do this. I just copied
this block from LTHI.

+}
+
 void SurfaceLayer::SetLayerTreeHost(LayerTreeHost* host) {
   if (layer_tree_host() == host) {
-    Layer::SetLayerTreeHost(host);
     return;
   }
+  const SurfaceId* surface_id = GetSurfaceId(host);
+
+  if (layer_tree_host() && surface_id) {
+    layer_tree_host()->RemoveSurfaceLayerId(*surface_id);
+  }
+
   RemoveReference(std::move(primary_reference_returner_));
   RemoveReference(std::move(fallback_reference_returner_));
   Layer::SetLayerTreeHost(host);
@@ -116,6 +146,8 @@ void SurfaceLayer::SetLayerTreeHost(LayerTreeHost* host) {
       fallback_reference_returner_ = ref_factory_->CreateReference(
           layer_tree_host(), fallback_surface_info_.id());
     }
+    if (surface_id)
+      layer_tree_host()->AddSurfaceLayerId(*surface_id);
   }
 }