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..53c85aa4ecd5b57235c476df6bf8adaa36f28721 100644
--- a/services/ui/surfaces/display_compositor.cc
+++ b/services/ui/surfaces/display_compositor.cc
@@ -14,32 +14,98 @@ DisplayCompositor::DisplayCompositor(
   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::AddRootSurfaceReference(const cc::SurfaceId& child_id) {
+  AddSurfaceReference(manager_.GetRootSurfaceId(), child_id);
+}
+
+void DisplayCompositor::AddSurfaceReference(const cc::SurfaceId& parent_id,
+                                            const cc::SurfaceId& child_id) {
+  auto vector_iter = temp_references_.find(child_id.frame_sink_id());
+
+  // If there are no temporary references for the FrameSinkId then we can just
+  // add reference and return.
+  if (vector_iter == temp_references_.end()) {
+    manager_.AddSurfaceReference(parent_id, child_id);
+    return;
+  }
+
+  // Get the vector<LocalFrameId> for the appropriate FrameSinkId and look for
+  // |child_id.local_frame_id| in that vector. If found, there is a temporary
+  // reference to |child_id|.
+  std::vector<cc::LocalFrameId>& refs = vector_iter->second;
+  auto temp_ref_iter =
+      std::find(refs.begin(), refs.end(), child_id.local_frame_id());
+
+  if (temp_ref_iter == refs.end()) {
+    manager_.AddSurfaceReference(parent_id, child_id);
     return;
   }
-  surface->AddDestructionDependency(surface_sequence);
+
+  // All surfaces get a temporary reference to the top level root. If the parent
+  // wants to add a reference to the top level root then we do nothing.
+  // Otherwise remove the temporary reference and add the reference.
+  if (parent_id != manager_.GetRootSurfaceId()) {
+    manager_.AddSurfaceReference(parent_id, child_id);
+    manager_.RemoveSurfaceReference(manager_.GetRootSurfaceId(), child_id);
+  }
+
+  // Remove temporary references for surfaces with the same FrameSinkId that
+  // were created before |child_id|. The earlier surfaces were never embedded in
+  // the parent and the parent is embedding a later surface, so we know the
+  // parent doesn't need them anymore.
+  for (auto iter = refs.begin(); iter != temp_ref_iter; ++iter) {
+    cc::SurfaceId id = cc::SurfaceId(child_id.frame_sink_id(), *iter);
+    manager_.RemoveSurfaceReference(manager_.GetRootSurfaceId(), id);
+  }
+
+  // Remove markers for temporary references up to |child_id|, as the temporary
+  // references they correspond to were removed above. If |ref_iter| is the last
+  // element in |refs| then we are removing all temporary references for the
+  // FrameSinkId and can remove the map entry entirely.
+  if (++temp_ref_iter == refs.end())
+    temp_references_.erase(child_id.frame_sink_id());
+  else
+    refs.erase(refs.begin(), ++temp_ref_iter);
 }
 
-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::RemoveRootSurfaceReference(
+    const cc::SurfaceId& child_id) {
+  RemoveSurfaceReference(manager_.GetRootSurfaceId(), child_id);
+}
+
+void DisplayCompositor::RemoveSurfaceReference(const cc::SurfaceId& parent_id,
+                                               const cc::SurfaceId& child_id) {
+  // TODO(kylechar): Each remove reference can trigger GC, it would be better if
+  // we GC only once if removing multiple references.
+  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(
+          manager_.GetRootSurfaceId(),
+          cc::SurfaceId(frame_sink_id, local_frame_id));
+    }
+  }
   manager_.RemoveObserver(this);
 }
 
 void DisplayCompositor::OnSurfaceCreated(const cc::SurfaceId& surface_id,
                                          const gfx::Size& frame_size,
                                          float device_scale_factor) {
+  // We can get into a situation where multiple CompositorFrames arrive for a
+  // CompositorFrameSink before the DisplayCompositorClient can add any
+  // references for the frame. When the second frame with a new size arrives,
+  // the first will be destroyed and then if there are no references it will be
+  // deleted during surface GC. A temporary reference, removed when a real
+  // reference is received, is added to prevent this from happening.
+  manager_.AddSurfaceReference(manager_.GetRootSurfaceId(), 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);
 }