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"
+
+namespace webkit_media {
+
+namespace {
+
+const char kClearKeyKeySystem[] = "webkit-org.w3.clearkey";

[scherkus (not reviewing), 2012/06/21 21:17:16]

this is declared in webkit/media/key_systems.cc -- can we dedupe?

[xhwang, 2012/06/22 16:57:30]

Will do.

[xhwang, 2012/06/26 23:45:50]

Done.

+
+}  // namespace
+
+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()) {
+    if (key_system == kClearKeyKeySystem) {
+      base::AutoLock auto_lock(lock_);
+      decryptor_.reset(new media::AesDecryptor(client_));

[scherkus (not reviewing), 2012/06/21 21:17:16]

is there a disadvantage to creating this in the ctor instead?

[xhwang, 2012/06/22 16:57:30]

Currently we don't allow run-time switching between selected decryptors. This is
to simplify the locking scheme we use and minimize the locking time (maybe it's
pre-mature optimization :P). By creating this in the ctor, we'll need to switch
from AesDecryptor to e.g. PpapiDecryptor at run-time.

+      current_key_system_ = key_system;
+    } else {
+      NOTREACHED();

[scherkus (not reviewing), 2012/06/21 21:17:16]

can these DCHECKs be triggered via JS? i.e., I call gKR() w/ "foo.blah.mycrypto"
?

[xhwang, 2012/06/22 16:57:30]

No. The WMPI will check IsSupportedKeySystem() and rule out unsupported key
system strings.

+    }
+  }
+
+  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() && key_system == current_key_system_);

[scherkus (not reviewing), 2012/06/21 21:17:16]

instead of && split the DCHECKs

[xhwang, 2012/06/22 16:57:30]

Will do.

[xhwang, 2012/06/26 23:45:50]

Done.

+  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() && key_system == current_key_system_);

[scherkus (not reviewing), 2012/06/21 21:17:16]

instead of && split the DCHECKs

[xhwang, 2012/06/22 16:57:30]

Will do.

[xhwang, 2012/06/26 23:45:50]

Done.

+  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