Mus+Ash: propagate Surface ID to parents

services/ui/public/cpp/window.cc

Index: services/ui/public/cpp/window.cc
diff --git a/services/ui/public/cpp/window.cc b/services/ui/public/cpp/window.cc
index 966e51888c18a26e688a91a45c1a44010347b7a9..15cdf0676e399bd73fe92183b3df2a78b2460bd2 100644
--- a/services/ui/public/cpp/window.cc
+++ b/services/ui/public/cpp/window.cc
@@ -533,6 +533,11 @@ Window::~Window() {
   if (transient_parent_)
     transient_parent_->LocalRemoveTransientWindow(this);
 
+  // Return the surface reference if there is one.
+  if (!surface_info_.surface_id.is_null())
+    LocalSetSurfaceId(cc::SurfaceId(), cc::SurfaceSequence(), gfx::Size(),
+                      1.0f);
+
   // Remove transient children.
   while (!transient_children_.empty()) {
     Window* transient_child = transient_children_.front();
@@ -790,6 +795,31 @@ void Window::LocalSetSharedProperty(const std::string& name,
       OnWindowSharedPropertyChanged(this, name, old_value_ptr, value));
 }
 
+void Window::LocalSetSurfaceId(const cc::SurfaceId& surface_id,
+                               const cc::SurfaceSequence& surface_sequence,
+                               const gfx::Size& frame_size,
+                               float device_scale_factor) {
+  const cc::SurfaceId& existing_surface_id = surface_info_.surface_id;
+  if (!existing_surface_id.is_null() && existing_surface_id != surface_id) {
+    // Return the existing surface sequence.
+    if (client_) {
+      client_->ReturnSurfaceReference(server_id_,
+                                      surface_info_.surface_sequence);
+    }
+  }
+  surface_info_ = {surface_id, surface_sequence, frame_size,
+                   device_scale_factor};
+  if (parent_) {
+    // TODO(fsamuel, sadrul): This assumes that observers just observe. If a
+    // ui::Layer is an observer here then it takes ownership of the
+    // SurfaceSequence and returning the refernece.
+    for (auto& observer : parent_->observers_) {
+      observer.OnChildWindowSurfaceCreated(this, surface_id, surface_sequence,
+                                           frame_size, device_scale_factor);
+    }
+  }
+}
+
 void Window::NotifyWindowStackingChanged() {
   if (stacking_target_) {
     Children::const_iterator window_i = std::find(