Add allocator interface for use by cdm_adapter

media/cdm/cdm_buffer_allocator_impl.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 MEDIA_CDM_CDM_BUFFER_ALLOCATOR_IMPL_H_
+#define MEDIA_CDM_CDM_BUFFER_ALLOCATOR_IMPL_H_
+
+#include <stdint.h>
+
+#include "base/macros.h"
+#include "media/base/media_export.h"
+#include "media/cdm/cdm_buffer_allocator.h"
+
+namespace media {
+
+// This is a simple CdmBufferAllocator that simply allocates a new
+// CdmBufferImpl on every Allocate() request. It does not keep track
+// of the memory allocated. The caller is responsible for calling Destroy()
+// on the returned buffer when it is no longer needed.

[xhwang, 2016/02/09 18:27:32]

How about Release()? Can Release() be called after Destroy()?

[jrummell, 2016/02/11 01:39:38]

Updated to mention Release() instead.

+class MEDIA_EXPORT CdmBufferAllocatorImpl : public CdmBufferAllocator {

[xhwang, 2016/02/09 18:27:32]

The "Impl" part makes it look like it'll be the default implementation to be
used in production.

Will we also have SharedMemoryCdmBufferAllocator? How about
s/CdmBufferAllocatorImpl/SimpleCdmBufferAllocator/? 

And the CdmBufferImpl can be SimpleCdmBuffer.

[jrummell, 2016/02/11 01:39:39]

Done.

+ public:
+  CdmBufferAllocatorImpl();
+  ~CdmBufferAllocatorImpl() override;
+
+  // CdmBufferAllocator implementation.
+  CdmBuffer* Allocate(uint32_t capacity) final;
+  void Release(uint32_t buffer_id) final;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(CdmBufferAllocatorImpl);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_CDM_CDM_BUFFER_ALLOCATOR_IMPL_H_