Remove som GYP annotations, remove unused manifest.

device/media_transfer_protocol/BUILD.gn

Index: device/media_transfer_protocol/BUILD.gn
diff --git a/device/media_transfer_protocol/BUILD.gn b/device/media_transfer_protocol/BUILD.gn
index e3c4dc32df8d239e387e6723bc01d7b156a9d296..d3ced9153f37dc1d0d4ebe797ab213514c708b59 100644
--- a/device/media_transfer_protocol/BUILD.gn
+++ b/device/media_transfer_protocol/BUILD.gn
@@ -7,7 +7,6 @@ import("//third_party/protobuf/proto_library.gni")
 
 assert(use_dbus)
 
-# GYP version: device/media_transfer_protocol/media_transfer_protocol.gyp:mtp_file_entry_proto
 proto_library("mtp_file_entry_proto") {
   sources = [
     "//third_party/cros_system_api/dbus/mtp_file_entry.proto",
@@ -15,7 +14,6 @@ proto_library("mtp_file_entry_proto") {
   proto_out_dir = "device/media_transfer_protocol"
 }
 
-# GYP version: device/media_transfer_protocol/media_transfer_protocol.gyp:mtp_storage_info_proto
 proto_library("mtp_storage_info_proto") {
   sources = [
     "//third_party/cros_system_api/dbus/mtp_storage_info.proto",
@@ -23,7 +21,6 @@ proto_library("mtp_storage_info_proto") {
   proto_out_dir = "device/media_transfer_protocol"
 }
 
-# GYP version: device/media_transfer_protocol:media_transfer_protocol.gyp:media_transfer_protocol
 static_library("media_transfer_protocol") {
   sources = [
     "media_transfer_protocol_daemon_client.cc",