Convert mustash use surface references.

services/ui/surfaces/display_compositor.cc

Index: services/ui/surfaces/display_compositor.cc
diff --git a/services/ui/surfaces/display_compositor.cc b/services/ui/surfaces/display_compositor.cc
index f8126c0e681c3edbb2958125bf80a217a0bff3bc..19655cfb05383db49383bb5b6925883b59616cb6 100644
--- a/services/ui/surfaces/display_compositor.cc
+++ b/services/ui/surfaces/display_compositor.cc
@@ -8,38 +8,76 @@
 
 namespace ui {
 
+namespace {}  // namespace

[Fady Samuel, 2016/11/10 13:53:02]

delete?

[kylechar, 2016/11/14 19:05:38]

Done.

+
 DisplayCompositor::DisplayCompositor(
     cc::mojom::DisplayCompositorClientPtr client)
     : client_(std::move(client)) {
   manager_.AddObserver(this);
 }
 
-void DisplayCompositor::AddSurfaceReference(
-    const cc::SurfaceId& surface_id,
-    const cc::SurfaceSequence& surface_sequence) {
-  cc::Surface* surface = manager_.GetSurfaceForId(surface_id);
-  if (!surface) {
-    LOG(ERROR) << "Attempting to add dependency to nonexistent surface "
-               << surface_id.ToString();
+void DisplayCompositor::AddSurfaceReference(const cc::SurfaceId& parent_id,
+                                            const cc::SurfaceId& child_id) {
+  // If there are no temporary references then we can just add.
+  if (temp_references_.count(child_id.frame_sink_id()) == 0) {
+    manager_.AddSurfaceReference(parent_id, child_id);
     return;
   }
-  surface->AddDestructionDependency(surface_sequence);
+
+  auto& refs = temp_references_[child_id.frame_sink_id()];
+  auto ref_iter =
+      std::find(refs.begin(), refs.end(), child_id.local_frame_id());

[Fady Samuel, 2016/11/10 13:53:02]

I was initially confused about what this is doing. A comment might be helpful.

[kylechar, 2016/11/14 19:05:38]

Done.

+
+  // Make sure not to double add reference here.
+  if (parent_id != cc::SurfaceManager::kRootSurfaceId || ref_iter == refs.end())
+    manager_.AddSurfaceReference(parent_id, child_id);
+
+  if (ref_iter == refs.end())
+    return;
+
+  // Don't remove temporary reference if it was the same as real reference.
+  if (parent_id != cc::SurfaceManager::kRootSurfaceId)

[Fady Samuel, 2016/11/10 13:53:02]

nit: Braces.

[kylechar, 2016/11/14 19:05:38]

Done.

+    manager_.RemoveSurfaceReference(cc::SurfaceManager::kRootSurfaceId,
+                                    child_id);
+
+  // Remove temporary references for earlier frames.
+  for (auto iter = refs.begin(); iter != ref_iter; ++iter) {
+    cc::SurfaceId id = cc::SurfaceId(child_id.frame_sink_id(), *iter);
+    manager_.RemoveSurfaceReference(cc::SurfaceManager::kRootSurfaceId, id);
+  }
+
+  refs.erase(refs.begin(), ++ref_iter);
+  if (refs.empty())
+    temp_references_.erase(child_id.frame_sink_id());
 }
 
-void DisplayCompositor::ReturnSurfaceReferences(
-    const cc::FrameSinkId& frame_sink_id,
-    const std::vector<uint32_t>& sequences) {
-  std::vector<uint32_t> sequences_copy(sequences);
-  manager_.DidSatisfySequences(frame_sink_id, &sequences_copy);
+void DisplayCompositor::RemoveSurfaceReference(const cc::SurfaceId& parent_id,
+                                               const cc::SurfaceId& child_id) {
+  manager_.RemoveSurfaceReference(parent_id, child_id);
 }
 
 DisplayCompositor::~DisplayCompositor() {
+  // Remove all temporary references on shutdown.
+  for (auto& map_entry : temp_references_) {
+    const cc::FrameSinkId& frame_sink_id = map_entry.first;
+    for (auto& local_frame_id : map_entry.second) {
+      manager_.RemoveSurfaceReference(
+          cc::SurfaceManager::kRootSurfaceId,
+          cc::SurfaceId(frame_sink_id, local_frame_id));
+    }
+  }
+  temp_references_.clear();
   manager_.RemoveObserver(this);
 }
 
 void DisplayCompositor::OnSurfaceCreated(const cc::SurfaceId& surface_id,
                                          const gfx::Size& frame_size,
                                          float device_scale_factor) {
+  // Add a temporary reference from the top level root to this surface.

[Fady Samuel, 2016/11/10 13:53:02]

A short description of why this temporary reference is necessary would be
useful.

[kylechar, 2016/11/14 19:05:38]

Done.

+  manager_.AddSurfaceReference(cc::SurfaceManager::kRootSurfaceId, surface_id);
+  temp_references_[surface_id.frame_sink_id()].push_back(
+      surface_id.local_frame_id());
+
   if (client_)
     client_->OnSurfaceCreated(surface_id, frame_size, device_scale_factor);
 }