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

webkit/media/crypto/proxy_decryptor.h

Index: webkit/media/crypto/proxy_decryptor.h
diff --git a/webkit/media/crypto/proxy_decryptor.h b/webkit/media/crypto/proxy_decryptor.h
index 61360ebaceb5f33235cdef782ae9d719ba2bf6a7..cd664fc6204bd7f27baa4bb709b00ec544722c41 100644
--- a/webkit/media/crypto/proxy_decryptor.h
+++ b/webkit/media/crypto/proxy_decryptor.h
@@ -6,11 +6,14 @@
 #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"
 
+class MessageLoop;
+
 namespace media {
 class DecryptorClient;
 }
@@ -53,6 +56,20 @@ class ProxyDecryptor : public media::Decryptor {
       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(
+      MessageLoop* message_loop,
+      const scoped_refptr<media::DecoderBuffer>& encrypted,
+      const media::Decryptor::DecryptCB& decrypt_cb);
+
+  // Callback used to pass into decryptor_->Decrypt().
+  void OnBufferDecrypted(MessageLoop* message_loop,
+                         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.
@@ -65,9 +82,13 @@ class ProxyDecryptor : public media::Decryptor {
   // 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_;
+  std::vector<base::Closure> pending_decrypt_closures_;
+
   DISALLOW_COPY_AND_ASSIGN(ProxyDecryptor);
 };