Allow layers to signal that additional sequences are needed before surface destruction

cc/layers/surface_holder.h

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CC_LAYERS_SURFACE_HOLDER_H_
+#define CC_LAYERS_SURFACE_HOLDER_H_
+
+#include <set>
+
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "cc/base/cc_export.h"
+#include "cc/surfaces/surface_id.h"
+#include "cc/surfaces/surface_sequence.h"
+
+namespace cc {
+
+class CC_EXPORT SurfaceHolder : public base::RefCounted<SurfaceHolder> {
+ public:
+  // The callback is called to satisfy a particular SurfaceSequence if the
+  // compositor is unable to.
+  typedef base::Callback<void(SurfaceSequence)> SatisfyCallback;
+  SurfaceHolder(SurfaceId id, SatisfyCallback satisfy_callback);
+
+  // Retrieves and clears the list of sequences that must be satisfied before
+  // surface destruction.
+  void GetSequenceSet(std::set<SurfaceSequence>* sequences);
+
+  // Adds a new sequence that must be satisfied before surface destruction.
+  void AddSurfaceSequence(SurfaceSequence sequence);
+
+  SatisfyCallback satisfy_callback() { return satisfy_callback_; }
+  SurfaceId surface_id() const { return id_; }
+
+ private:
+  friend class base::RefCounted<SurfaceHolder>;
+  ~SurfaceHolder();
+
+  SurfaceId id_;
+  SatisfyCallback satisfy_callback_;
+  std::set<SurfaceSequence> sequences_;

[piman, 2014/11/03 23:49:26]

nit: hash_set? Faster/less memory?
Or even, if you don't expect many of these, maybe just a simple vector?

[danakj, 2014/11/04 16:56:57]

hash_set may be slower on android (due to modulo operation, integer division
sucks there)? +1 to vector though for small sets.

+
+  DISALLOW_COPY_AND_ASSIGN(SurfaceHolder);
+};
+
+}  // namespace cc
+
+#endif  // CC_LAYERS_SURFACE_HOLDER_H_