Add allocator interface for use by cdm_adapter

media/cdm/simple_cdm_buffer.cc

Index: media/cdm/simple_cdm_buffer.cc
diff --git a/media/cdm/simple_cdm_buffer.cc b/media/cdm/simple_cdm_buffer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4ed9f7bccebb0e3e82b78c4e3f218e437f2714cb
--- /dev/null
+++ b/media/cdm/simple_cdm_buffer.cc
@@ -0,0 +1,52 @@
+// Copyright 2015 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 "media/cdm/simple_cdm_buffer.h"
+
+#include "base/bind.h"
+#include "base/logging.h"
+#include "media/cdm/cdm_buffer_allocator.h"
+#include "media/cdm/cdm_helpers.h"
+
+namespace media {
+
+// static
+scoped_refptr<SimpleCdmBuffer> SimpleCdmBuffer::Create(
+    CdmBufferAllocator* allocator,
+    uint32_t capacity) {
+  DCHECK(capacity);
+  return new SimpleCdmBuffer(allocator, capacity);
+}
+
+SimpleCdmBuffer::SimpleCdmBuffer(CdmBufferAllocator* allocator,
+                                 uint32_t capacity)
+    : allocator_(allocator), buffer_(capacity), size_(0) {}
+
+SimpleCdmBuffer::~SimpleCdmBuffer() {}
+
+void SimpleCdmBuffer::Destroy() {
+  // Note that the CDM called AddRef() when allocating this object. However,
+  // passing |this| to Release() will casue the reference count to be
+  // decremented to match that AddRef().
+  allocator_->Release(this);

[xhwang, 2016/02/11 19:24:14]

See comment above. Destroy() should call Release() (opposite of AddRef()) to
release the ref-count we manually added in CdmAdapter::Allocate().

This could trigger the destruction of SimpleCdmBuffer if no one else is holding
a reference.

Then in the destructor, we can notify the Allocator. The allocator can recycle
the internal buffer (e.g. shared memory) if necessary.

Note that we don't have to pass in the |allocator| explicitly. Instead  we can
have a destruction callback which will be called in the dtor of the CdmBuffer.
This is similar to the destruction callback in media::VdieoFrame.

[jrummell, 2016/02/11 22:08:16]

No longer ref-counted, so we can simply call the destructor.

+}
+
+uint32_t SimpleCdmBuffer::Capacity() const {
+  return buffer_.size();
+}
+
+uint8_t* SimpleCdmBuffer::Data() {
+  return buffer_.data();
+}
+
+void SimpleCdmBuffer::SetSize(uint32_t size) {
+  DCHECK(size <= Capacity());
+  size_ = size > Capacity() ? 0 : size;
+}
+
+uint32_t SimpleCdmBuffer::Size() const {
+  return size_;
+}
+
+}  // namespace media