Add PpapiDecryptor which wraps a CDM plugin.

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 335bdafb22935190f1e9158fc3fa4012b377aa7c..7365afd17b36708653533e1b4689b84455dad754 100644
--- a/webkit/media/crypto/proxy_decryptor.h
+++ b/webkit/media/crypto/proxy_decryptor.h
@@ -10,6 +10,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
 #include "media/base/decryptor.h"
+#include "webkit/media/crypto/key_systems.h"
 
 namespace media {
 class DecryptorClient;
@@ -23,7 +24,8 @@ namespace webkit_media {
 // objects. Fix this when needed.
 class ProxyDecryptor : public media::Decryptor {
  public:
-  explicit ProxyDecryptor(media::DecryptorClient* client);
+  explicit ProxyDecryptor(media::DecryptorClient* client,
+                          const CreatePluginCB& create_plugin_cb);
   virtual ~ProxyDecryptor();
 
   // media::Decryptor implementation.
@@ -43,6 +45,7 @@ class ProxyDecryptor : public media::Decryptor {
 
  private:
   media::DecryptorClient* const client_;
+  CreatePluginCB create_plugin_cb_;
   // 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