Add ProxyDecryptor which wraps concrete Decryptor implementations.

webkit/media/crypto/proxy_decryptor.cc

+// 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.
+
+#include "webkit/media/crypto/proxy_decryptor.h"
+
+#include "base/logging.h"
+#include "media/base/decoder_buffer.h"
+#include "media/base/decryptor_client.h"
+#include "media/crypto/aes_decryptor.h"
+#include "webkit/media/crypto/key_systems.h"
+
+namespace webkit_media {
+
+ProxyDecryptor::ProxyDecryptor(media::DecryptorClient* client)
+    : client_(client) {
+}
+
+ProxyDecryptor::~ProxyDecryptor() {
+}
+
+void ProxyDecryptor::GenerateKeyRequest(const std::string& key_system,
+                                        const uint8* init_data,
+                                        int init_data_length) {
+  // We do not support run-time switching of decryptors. GenerateKeyRequest()
+  // should only be called when the decryptor is not initialized, or on the
+  // existing decryptor associated with the |current_key_system_|.
+  DCHECK(!decryptor_.get() || key_system == current_key_system_);
+
+  if (!decryptor_.get()) {

[ddorwin, 2012/06/27 04:00:08]

Do we assume that decryptor_ is set always on the same thread (and thus do not
need to lock it)? If so, that's worth commenting.

[xhwang, 2012/06/27 21:41:26]

Added comment about |lock_| in .h file.

+    if (key_system == kClearKeyKeySystem) {
+      base::AutoLock auto_lock(lock_);

[ddorwin, 2012/06/27 04:00:08]

If we don't need to lock above, why are we locking here? If there is no
decryptor, nobody is using it, right? Or can the decoder be using it before we
create one. I'm guessing that's the reason. If so, this is also worth a comment.

[xhwang, 2012/06/27 21:41:26]

Added comment about |lock_| in .h file.

+      decryptor_.reset(new media::AesDecryptor(client_));
+      current_key_system_ = key_system;
+    } else {
+      NOTREACHED();
+    }
+  }
+
+  decryptor_->GenerateKeyRequest(key_system, init_data, init_data_length);
+}
+
+void ProxyDecryptor::AddKey(const std::string& key_system,
+                            const uint8* key,
+                            int key_length,
+                            const uint8* init_data,
+                            int init_data_length,
+                            const std::string& session_id) {
+  DCHECK(decryptor_.get());

[ddorwin, 2012/06/27 04:00:08]

 // WMPI ensures GenerateKeyRequest() has been called.
Is that right?
Same below.

[xhwang, 2012/06/27 21:41:26]

Done.

+  DCHECK_EQ(current_key_system_, key_system);
+  decryptor_->AddKey(key_system, key, key_length, init_data, init_data_length,
+                     session_id);
+}
+
+void ProxyDecryptor::CancelKeyRequest(const std::string& key_system,
+                                      const std::string& session_id) {
+  DCHECK(decryptor_.get());
+  DCHECK_EQ(current_key_system_, key_system);
+  decryptor_->CancelKeyRequest(key_system, session_id);
+}
+
+scoped_refptr<media::DecoderBuffer> ProxyDecryptor::Decrypt(
+    const scoped_refptr<media::DecoderBuffer>& input) {
+  // This is safe as we do not replace/delete an existing decryptor at run-time.
+  Decryptor* decryptor = NULL;
+  {
+    base::AutoLock auto_lock(lock_);
+    decryptor = decryptor_.get();
+  }
+  if (!decryptor)
+    return NULL;
+
+  return decryptor->Decrypt(input);
+}
+
+}  // namespace webkit_media