Introducing SurfaceReferenceFactory

cc/surfaces/sequence_surface_reference_factory.cc

+// Copyright 2016 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.
+
+#include "cc/surfaces/sequence_surface_reference_factory.h"
+
+#include "cc/surfaces/sequence_surface_reference.h"
+
+namespace cc {
+
+std::unique_ptr<SurfaceReferenceBase>
+SequenceSurfaceReferenceFactory::CreateReference(
+    SurfaceReferenceOwner* owner,
+    const SurfaceId& surface_id) const {
+  auto seq = owner->GetSurfaceSequenceGenerator()->CreateSurfaceSequence();
+  RequireSequence(surface_id, seq);
+  return base::MakeUnique<SequenceSurfaceReference>(make_scoped_refptr(this),
+                                                    seq);
+}
+
+void SequenceSurfaceReferenceFactory::DestroyReference(
+    SurfaceReferenceBase* surface_ref) const {
+  // This method can only be called by a SurfaceReferenceBase because it's
+  // private and only SurfaceReferenceBase is a friend. The reference only
+  // calls this method on the factory that created it. So it's safe to cast
+  // the passed reference to the type returned by CreateReference.
+  auto ref = static_cast<SequenceSurfaceReference*>(surface_ref);
+  SatisfySequence(ref->sequence());
+}
+
+}  // namespace cc