Convert mustash use surface references.

services/ui/ws/frame_generator.h

Index: services/ui/ws/frame_generator.h
diff --git a/services/ui/ws/frame_generator.h b/services/ui/ws/frame_generator.h
index ed38ee24dad99e4e8491a23c48728f1c50f0f0f3..ef3e5028dd2badceb18abc18d53049747e2caecc 100644
--- a/services/ui/ws/frame_generator.h
+++ b/services/ui/ws/frame_generator.h
@@ -11,9 +11,7 @@
 #include "base/macros.h"
 #include "base/timer/timer.h"
 #include "cc/surfaces/frame_sink_id.h"
-#include "cc/surfaces/local_frame_id.h"
-#include "cc/surfaces/surface_sequence.h"
-#include "cc/surfaces/surface_sequence_generator.h"
+#include "cc/surfaces/surface_id.h"
 #include "services/ui/public/interfaces/window_tree_constants.mojom.h"
 #include "services/ui/ws/ids.h"
 #include "services/ui/ws/server_window_tracker.h"
@@ -56,6 +54,21 @@ class FrameGenerator : public ServerWindowTracker,
   // Schedules a redraw for the provided region.
   void OnAcceleratedWidgetAvailable(gfx::AcceleratedWidget widget);
 
+  // Adds a reference to new surface with |surface_id| for |window|. This
+  // reference is to ensure the surface is not deleted while it's still being
+  // displayed. The display root surface has a reference from the top level
+  // root. All child surfaces are embedded by the display root and receive a
+  // reference from it.
+  //
+  // If a new display root Surface is created, then all child surfaces will
+  // receive a reference from the new display root so they are not deleted with
+  // the old display root.
+  //
+  // If there is an existing reference to an old surface with the same
+  // FrameSinkId then that reference will be removed after the next
+  // CompositorFrame is submitted.
+  void OnSurfaceCreated(const cc::SurfaceId& surface_id, ServerWindow* window);
+
  private:
   friend class ui::ws::test::FrameGeneratorTest;
 
@@ -74,27 +87,30 @@ class FrameGenerator : public ServerWindowTracker,
                       const gfx::Vector2d& parent_to_root_origin_offset,
                       float opacity);
 
-  // Adds a reference to the current cc::Surface of the provided
-  // |window_compositor_frame_sink|. If an existing reference is held with a
-  // different LocalFrameId then release that reference first. This is called on
-  // each ServerWindowCompositorFrameSink as FrameGenerator walks the window
-  // tree to generate a CompositorFrame. This is done to make sure that the
-  // window surfaces are retained for the entirety of the time between
-  // submission of the top-level frame to drawing the frame to screen.
-  // TODO(fsamuel, kylechar): This will go away once we get surface lifetime
-  // management.
-  void AddOrUpdateSurfaceReference(mojom::CompositorFrameSinkType type,
-                                   ServerWindow* window);
-
-  // Releases any retained references for the provided FrameSink.
-  // TODO(fsamuel, kylechar): This will go away once we get surface lifetime
-  // management.
-  void ReleaseFrameSinkReference(const cc::FrameSinkId& frame_sink_id);
-
-  // Releases all retained references to surfaces.
-  // TODO(fsamuel, kylechar): This will go away once we get surface lifetime
-  // management.
-  void ReleaseAllSurfaceReferences();
+  // Finds the parent surface id for |window|.
+  cc::SurfaceId FindParentSurfaceId(ServerWindow* window);
+
+  // Adds surface reference to local cache and surface manager.
+  void AddSurfaceReference(const cc::SurfaceId& parent_id,
+                           const cc::SurfaceId& child_id);
+
+  // Does work necessary for adding the first surface reference.
+  void AddFirstReference(const cc::SurfaceId& surface_id, ServerWindow* window);
+
+  // Finds all Surfaces with references from |old_surface_id| and adds a new
+  // reference from |new_surface_id|. The caller should remove any references
+  // to |old_surface_id| afterwards to finish cleanup.
+  void AddNewParentReferences(const cc::SurfaceId& old_surface_id,
+                              const cc::SurfaceId& new_surface_id);
+
+  // Removes all references to surfaces in |dead_references_|.
+  void RemoveDeadSurfaceReferences();
+
+  // Removes any retained references for the provided FrameSink.
+  void RemoveFrameSinkReference(const cc::FrameSinkId& frame_sink_id);
+
+  // Removes all retained references to surfaces.
+  void RemoveAllSurfaceReferences();
 
   ui::DisplayCompositor* GetDisplayCompositor();
 
@@ -102,20 +118,36 @@ class FrameGenerator : public ServerWindowTracker,
   void OnWindowDestroying(ServerWindow* window) override;
 
   FrameGeneratorDelegate* delegate_;
-  cc::FrameSinkId frame_sink_id_;
   ServerWindow* const root_window_;
-  cc::SurfaceSequenceGenerator surface_sequence_generator_;
   scoped_refptr<gpu::GpuChannelHost> gpu_channel_;
 
   cc::mojom::MojoCompositorFrameSinkPtr compositor_frame_sink_;
   gfx::AcceleratedWidget widget_ = gfx::kNullAcceleratedWidget;
 
-  struct SurfaceDependency {
-    cc::LocalFrameId local_frame_id;
-    cc::SurfaceSequence sequence;
+  // Represents the top level root surface id that should reference the display
+  // root surface. We don't know the actual value, because it's generated in
+  // another process, this is used internally as a placeholder.
+  const cc::SurfaceId top_level_root_surface_id_;
+
+  struct SurfaceReference {
+    cc::SurfaceId parent_id;
+    cc::SurfaceId child_id;
   };
-  std::unordered_map<cc::FrameSinkId, SurfaceDependency, cc::FrameSinkIdHash>
-      dependencies_;
+
+  // Active references held by this client to surfaces that could be embedded in
+  // a CompositorFrame submitted from FrameGenerator.
+  std::unordered_map<cc::FrameSinkId, SurfaceReference, cc::FrameSinkIdHash>
+      active_references_;
+
+  // References to surfaces that should be removed after a CompositorFrame has
+  // been submitted and the surfaces are not being used.
+  std::vector<SurfaceReference> dead_references_;
+
+  // If a CompositorFrame for a child surface is submitted before the first
+  // display root CompositorFrame, we can't add a reference from the unknown
+  // display root SurfaceId. Track the child SurfaceId here and add a reference
+  // to it when the display root SurfaceId is available.
+  std::vector<cc::SurfaceId> waiting_for_references_;
 
   mojo::Binding<cc::mojom::MojoCompositorFrameSinkClient> binding_;