Convert between |init_data_type| and content type.

content/renderer/media/crypto/proxy_decryptor.cc

Index: content/renderer/media/crypto/proxy_decryptor.cc
diff --git a/content/renderer/media/crypto/proxy_decryptor.cc b/content/renderer/media/crypto/proxy_decryptor.cc
index 28cd421e85ff099858007c541c025fd594b92bc0..b6b900847063a536f6006dbae723e1863b796574 100644
--- a/content/renderer/media/crypto/proxy_decryptor.cc
+++ b/content/renderer/media/crypto/proxy_decryptor.cc
@@ -128,8 +128,19 @@ bool ProxyDecryptor::GenerateKeyRequest(const std::string& content_type,
   media::MediaKeys::SessionType session_type =
       persistent ? media::MediaKeys::PERSISTENT_SESSION
                  : media::MediaKeys::TEMPORARY_SESSION;
-  media_keys_->CreateSession(
-      content_type, init_data, init_data_length, session_type, promise.Pass());
+
+  // Translate content types.

[ddorwin, 2014/08/13 21:43:34]

nit: "Convert MIME type's used in the prefixed implementation."

[sandersd (OOO until July 31), 2014/08/13 21:50:58]

Done.

+  std::string init_data_type;
+  if (content_type == "audio/mp4" || content_type == "video/mp4") {
+    init_data_type = "cenc";
+  } else if (content_type == "audio/webm" || content_type == "video/webm") {
+    init_data_type = "webm";
+  } else {
+    init_data_type = content_type;

[ddorwin, 2014/08/13 21:43:34]

I wonder if we can add NOTREACHED(). If it only comes from ChunkDemuxer or
WMPA/WMPI, we know the values.

[sandersd (OOO until July 31), 2014/08/13 21:50:58]

Well, it's worth a try.

+  }
+
+  media_keys_->CreateSession(init_data_type, init_data, init_data_length,
+                             session_type, promise.Pass());
   return true;
 }