Implement "Key Presence" step in "Encrypted Block Encounted" algorithm in EME.

webkit/media/crypto/proxy_decryptor.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_PROXY_DECRYPTOR_H_
 #define WEBKIT_MEDIA_CRYPTO_PROXY_DECRYPTOR_H_
 
 #include <string>
+#include <vector>
 
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "media/base/decryptor.h"
 
+namespace base {
+class MessageLoopProxy;
+}
+
 namespace media {
 class DecryptorClient;
 }
 
 namespace WebKit {
 class WebFrame;
 class WebMediaPlayerClient;
 }
 
 namespace webkit_media {
 
 // A decryptor proxy that creates a real decryptor object on demand and
 // forwards decryptor calls to it.
 // TODO(xhwang): Currently we don't support run-time switching among decryptor
 // objects. Fix this when needed.
 class ProxyDecryptor : public media::Decryptor {
  public:
   ProxyDecryptor(media::DecryptorClient* decryptor_client,
                  WebKit::WebMediaPlayerClient* web_media_player_client,
                  WebKit::WebFrame* web_frame);
   virtual ~ProxyDecryptor();
 
+  // This is only for testing purpose.

[scherkus (not reviewing), 2012/07/28 23:07:19]

instead of a comment + setter that looks like it's not for testing, how about:
  1) Drop the comment
  2) Change fn to set_decryptor_for_testing()

[xhwang, 2012/07/30 19:58:10]

Done.

+  void set_decryptor(scoped_ptr<media::Decryptor> decryptor) {
+    decryptor_ = decryptor.Pass();
+  }
+
   // media::Decryptor implementation.
   virtual void GenerateKeyRequest(const std::string& key_system,
                                   const uint8* init_data,
                                   int init_data_length) OVERRIDE;
   virtual void 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) OVERRIDE;
   virtual void CancelKeyRequest(const std::string& key_system,
                                 const std::string& session_id) OVERRIDE;
   virtual void Decrypt(const scoped_refptr<media::DecoderBuffer>& encrypted,
                        const DecryptCB& decrypt_cb) OVERRIDE;
 
  private:
   scoped_ptr<media::Decryptor> CreatePpapiDecryptor(
       const std::string& key_system);
   scoped_ptr<media::Decryptor> CreateDecryptor(const std::string& key_system);
 
+  // Helper function that makes sure decryptor_->Decrypt() runs on the
+  // |message_loop|.
+  void DecryptOnMessageLoop(
+      const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy,
+      const scoped_refptr<media::DecoderBuffer>& encrypted,
+      const media::Decryptor::DecryptCB& decrypt_cb);
+
+  // Callback used to pass into decryptor_->Decrypt().
+  void OnBufferDecrypted(
+      const scoped_refptr<base::MessageLoopProxy>& message_loop_proxy,
+      const scoped_refptr<media::DecoderBuffer>& encrypted,
+      const media::Decryptor::DecryptCB& decrypt_cb,
+      media::Decryptor::DecryptStatus status,
+      const scoped_refptr<media::DecoderBuffer>& decrypted);
+
   media::DecryptorClient* client_;
 
   // Needed to create the PpapiDecryptor.
   WebKit::WebMediaPlayerClient* web_media_player_client_;
   WebKit::WebFrame* web_frame_;
 
   // Protects the |decryptor_|. The Decryptor interface specifies that the
   // Decrypt() function will be called on the decoder thread and all other
   // methods on the renderer thread. The |decryptor_| itself is thread safe
   // when this rule is obeyed. This lock is solely to prevent the race condition
   // between setting the |decryptor_| in GenerateKeyRequest() and using it in
   // Decrypt().
-  base::Lock lock_;
+  base::Lock decryptor_lock_;
   scoped_ptr<media::Decryptor> decryptor_;  // Protected by the |lock_|.
 
+  // Protects the |pending_decrypt_closures_|.
+  base::Lock pending_decrypt_closures_lock_;

[scherkus (not reviewing), 2012/07/28 23:07:19]

see my other comment -- we don't need this

[xhwang, 2012/07/30 19:58:10]

Done.

+  std::vector<base::Closure> pending_decrypt_closures_;
+
   DISALLOW_COPY_AND_ASSIGN(ProxyDecryptor);
 };
 
 }  // namespace webkit_media
 
 #endif  // WEBKIT_MEDIA_CRYPTO_PROXY_DECRYPTOR_H_