Generalize AesDecryptor to make it more spec compliant.

media/webm/webm_stream_parser.cc

Index: media/webm/webm_stream_parser.cc
diff --git a/media/webm/webm_stream_parser.cc b/media/webm/webm_stream_parser.cc
index bd031484e8713542a52d2170253e708ba2033a74..bddf8e3943cefb0cc2d04cb0ceef9314882d9c76 100644
--- a/media/webm/webm_stream_parser.cc
+++ b/media/webm/webm_stream_parser.cc
@@ -190,20 +190,20 @@ void WebMStreamParser::Init(const InitCB& init_cb,
                             const NewConfigCB& config_cb,
                             const NewBuffersCB& audio_cb,
                             const NewBuffersCB& video_cb,
-                            const KeyNeededCB& key_needed_cb) {
+                            const NeedKeyCB& need_key_cb) {
   DCHECK_EQ(state_, kWaitingForInit);
   DCHECK(init_cb_.is_null());
   DCHECK(!init_cb.is_null());
   DCHECK(!config_cb.is_null());
   DCHECK(!audio_cb.is_null() || !video_cb.is_null());
-  DCHECK(!key_needed_cb.is_null());
+  DCHECK(!need_key_cb.is_null());
 
   ChangeState(kParsingHeaders);
   init_cb_ = init_cb;
   config_cb_ = config_cb;
   audio_cb_ = audio_cb;
   video_cb_ = video_cb;
-  key_needed_cb_ = key_needed_cb;
+  need_key_cb_ = need_key_cb;
 }
 
 void WebMStreamParser::Flush() {
@@ -343,7 +343,7 @@ int WebMStreamParser::ParseInfoAndTracks(const uint8* data, int size) {
     CHECK_GT(key_id_size, 0);
     scoped_array<uint8> key_id(new uint8[key_id_size]);
     memcpy(key_id.get(), tracks_parser.video_encryption_key_id(), key_id_size);
-    key_needed_cb_.Run(key_id.Pass(), key_id_size);
+    need_key_cb_.Run(key_id.Pass(), key_id_size);
   }
 
   cluster_parser_.reset(new WebMClusterParser(