[cc] Adds source_id and sequence_number to BeginFrameArgs.

cc/ipc/begin_frame_args_struct_traits.h

Index: cc/ipc/begin_frame_args_struct_traits.h
diff --git a/cc/ipc/begin_frame_args_struct_traits.h b/cc/ipc/begin_frame_args_struct_traits.h
index bf3c5a802ed6c61ee718e5cf3e3b1515125f4d27..98b02d631b5dcb8a16015ed7bbbf4de6acda9252 100644
--- a/cc/ipc/begin_frame_args_struct_traits.h
+++ b/cc/ipc/begin_frame_args_struct_traits.h
@@ -12,6 +12,14 @@ namespace mojo {
 
 template <>
 struct StructTraits<cc::mojom::BeginFrameArgsDataView, cc::BeginFrameArgs> {
+  static uint32_t source_id(const cc::BeginFrameArgs& args) {
+    return args.source_id;
+  }
+
+  static uint64_t sequence_number(const cc::BeginFrameArgs& args) {
+    return args.sequence_number;
+  }
+
   static base::TimeTicks frame_time(const cc::BeginFrameArgs& args) {
     return args.frame_time;
   }
@@ -39,6 +47,8 @@ struct StructTraits<cc::mojom::BeginFrameArgsDataView, cc::BeginFrameArgs> {
         !data.ReadInterval(&out->interval)) {
       return false;
     }
+    out->source_id = data.source_id();
+    out->sequence_number = data.sequence_number();
     out->type =
         static_cast<cc::BeginFrameArgs::BeginFrameArgsType>(data.type());
     out->on_critical_path = data.on_critical_path();