[Mojo Video Capture] Introduce abstraction BuildableVideoCaptureDevice

content/browser/renderer_host/media/ownership.h

Index: content/browser/renderer_host/media/ownership.h
diff --git a/content/browser/renderer_host/media/ownership.h b/content/browser/renderer_host/media/ownership.h
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+++ b/content/browser/renderer_host/media/ownership.h
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+// 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 CONTENT_BROWSER_RENDERER_HOST_MEDIA_OWNERSHIP_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MEDIA_OWNERSHIP_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/memory/ptr_util.h"
+#include "base/memory/ref_counted.h"
+
+namespace content {
+
+// Destructor-only interface for encapsulating pure ownership.
+// TODO(chfremer): Consider renaming this to Releasable, ScopedOpaqueReference,
+// ScopedReference, or ScopedResource.
+class Ownership {
+ public:
+  virtual ~Ownership() {}
+};
+
+// Encapsulates (shared) ownership of a scoped_refptr<T> and exposes it
+// through the Ownership interface.
+template <typename T>
+class ScopedRefptrOwnership : public Ownership {
+ public:
+  ScopedRefptrOwnership(scoped_refptr<T> refptr) : refptr_(std::move(refptr)) {}
+
+ private:
+  const scoped_refptr<T> refptr_;
+};
+
+template <typename T>
+std::unique_ptr<Ownership> MakeScopedRefptrOwnership(scoped_refptr<T> refptr) {
+  return base::MakeUnique<ScopedRefptrOwnership<T>>(std::move(refptr));
+}
+
+// A collection of Ownerships
+class OwnershipCollection : public Ownership {
+ public:
+  OwnershipCollection();
+  ~OwnershipCollection() override;
+
+  void AttachOwnership(std::unique_ptr<Ownership> ownership) {
+    collection_.push_back(std::move(ownership));
+  }
+
+ private:
+  std::vector<std::unique_ptr<Ownership>> collection_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MEDIA_OWNERSHIP_H_