Encrypted Media: Add TRACE_EVENT to trace eme implementation performance.

webkit/plugins/ppapi/ppapi_plugin_instance.cc

Index: webkit/plugins/ppapi/ppapi_plugin_instance.cc
diff --git a/webkit/plugins/ppapi/ppapi_plugin_instance.cc b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
index 57e157f1b71ee6fa03a21d1ea653908ff6db3ef0..db8b31ea5e55dca7f96c48f076c7b206836d3f7c 100644
--- a/webkit/plugins/ppapi/ppapi_plugin_instance.cc
+++ b/webkit/plugins/ppapi/ppapi_plugin_instance.cc
@@ -1920,6 +1920,8 @@ bool PluginInstance::DecryptAndDecodeVideo(
 
   const uint32_t request_id = next_decryption_request_id_++;
   DVLOG(2) << "DecryptAndDecodeVideo() - request_id " << request_id;
+  TRACE_EVENT_ASYNC_BEGIN0(
+      "eme", "PluginInstance::DecryptAndDecodeVideo", request_id);
 
   PP_EncryptedBlockInfo block_info;
   if (!MakeEncryptedBlockInfo(
@@ -2752,6 +2754,9 @@ void PluginInstance::DeliverFrame(PP_Instance instance,
     return;
   }
 
+  TRACE_EVENT_ASYNC_END0(
+      "eme", "PluginInstance::DecryptAndDecodeVideo", request_id);
+
   DCHECK(!pending_video_decode_cb_.is_null());
   pending_video_decode_request_id_ = 0;
   media::Decryptor::VideoDecodeCB video_decode_cb =