Introducing SurfaceReferenceFactory

cc/surfaces/surface_reference_base.h

+// 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.
+
+#ifndef CC_SURFACES_SURFACE_REFERENCE_BASE_H_
+#define CC_SURFACES_SURFACE_REFERENCE_BASE_H_
+
+#include <memory>
+
+#include "base/memory/ptr_util.h"
+#include "cc/surfaces/surface_reference_factory.h"
+#include "cc/surfaces/surface_sequence.h"
+
+namespace cc {
+
+class CompositorFrameMetadata;
+class SurfaceReferenceFactory;
+
+// The base class for the references returned by SurfaceReferenceFactory and
+// its subclasses.
+// The objects of this class hold on to their corresponding surface reference
+// until destroy is called.
+// To keep things as lightweight as possible, the base class only keeps a

[Fady Samuel, 2016/12/14 20:11:39]

I wouldn't say it's to keep things lightweight but to keep the representation of
a reference flexible you only keep a pointer to the factory in the base and
subclasses decide what other info they need to keep.

[Saman Sami, 2016/12/14 20:47:52]

But more information never hurts flexibility. I can keep surface id and owner,
but I don't because not all subclasses might want to use them and it will be an
unnecessary overhead.

+// pointer to the factory and it's up to the subclasses to decide what other
+// information they need to keep.
+class SurfaceReferenceBase {
+ public:
+  explicit SurfaceReferenceBase(
+      scoped_refptr<const SurfaceReferenceFactory> factory);
+  virtual ~SurfaceReferenceBase();
+
+  void Destroy();
+
+  // TODO(fsamuel, samans, kylechar): Remove this.
+  void Destroy(CompositorFrameMetadata* metadata);
+
+ private:
+  scoped_refptr<const SurfaceReferenceFactory> factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(SurfaceReferenceBase);
+};
+
+}  // namespace cc
+
+#endif  // CC_SURFACES_SURFACE_REFERENCE_BASE_H_