Add ProxyDecryptor which wraps concrete Decryptor implementations.

webkit/media/crypto/key_systems.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/key_systems.h"
+#include "webkit/media/crypto/key_systems.h"
 
+#include "media/base/decryptor.h"
+#include "media/crypto/aes_decryptor.h"
 #include "third_party/WebKit/Source/WebKit/chromium/public/platform/WebString.h"
 
 namespace webkit_media {
 
 namespace {
 
 const char kClearKeyKeySystem[] = "webkit-org.w3.clearkey";
 
 struct MediaFormatAndKeySystem {
   const char* mime_type;
@@ skipping 51 matching lines @@
 
   for (size_t i = 0; i < codecs.size(); ++i) {
     if (!IsSupportedKeySystemWithContainerAndCodec(
             mime_type, codecs[i], key_system))
       return false;
   }
 
   return true;
 }
 
+scoped_ptr<media::Decryptor> CreateDecryptor(const std::string& key_system,
+                                             media::DecryptorClient* client) {
+  if (key_system == kClearKeyKeySystem)
+    return scoped_ptr<media::Decryptor>(new media::AesDecryptor(client));
+  return scoped_ptr<media::Decryptor>();
+}
+
 }  // namespace webkit_media