Add CDM allocator interface.

webkit/media/crypto/ppapi/cdm_allocator.h

+// Copyright (c) 2012 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 WEBKIT_MEDIA_CRYPTO_PPAPI_CDM_ALLOCATOR_H_
+#define WEBKIT_MEDIA_CRYPTO_PPAPI_CDM_ALLOCATOR_H_
+
+#if defined(_MSC_VER)
+typedef unsigned char uint8_t;
+typedef int int32_t;
+#else
+#include <stdint.h>
+#endif
+
+namespace webkit_media {
+
+// Interface class intended to hide the PPAPI memory allocation implementation

[ddorwin, 2012/09/04 09:53:15]

Shouldn't mention PPAPI. It really addresses the cross-shared object allocation
issues and PPAPI is an implementation detail.

[Tom Finegan, 2012/09/07 00:46:36]

Done.

+// details from CDMs (Content Decryption Modules). The class implementing the
+// interface handles allocation. The data will be freed when the last reference

[ddorwin, 2012/09/04 09:53:15]

"The CDM wrapper takes ownership of the allocated data when it is returned to
the wrapper by the CDM (i.e. by DeliverBlock)."

^ I think that summarizes what really happens without going into details.

[Tom Finegan, 2012/09/07 00:46:36]

Done.

+// to the shared memory is released (typically after the browser has received
+// data from the CDM wrapper).
+class CdmAllocator {

[ddorwin, 2012/09/04 09:53:15]

Should this just be in CDM.h or is there a good reason to have a separate file?

[Tom Finegan, 2012/09/07 00:46:36]

Deleted cdm_allocator.h, and moved CdmAllocator to CDM.h.

+ public:
+  CdmAllocator() {}
+  virtual ~CdmAllocator() {}
+
+  // Returns a pointer to shared memory, or NULL on failure.
+  // Note: The memory returned is already mapped.
+  virtual uint8_t* Allocate(int32_t size, int32_t* id) = 0;

[ddorwin, 2012/09/04 09:53:15]

To further abstract things and ensure that things get deleted correctly: Does it
make sense to return and pass around a CdmBuffer object that contains the
pointer and ID values? Really, it's just:
class CdmBuffer { uint8_t* getBuffer(); int32_t getBufferSize(); }
The pointer and ID would be stored and only available within the PpbCdemBuffer
subclass.

[Tom Finegan, 2012/09/07 00:46:36]

Added CdmBuffer to CDM.h.

+};
+
+}  // namespace webkit_media;
+
+#endif  // WEBKIT_MEDIA_CRYPTO_PPAPI_CDM_ALLOCATOR_H_