[cc] Pass on BeginFrameAcks from CompositorEBFS through RWHVAura, DFH.

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 4d813395c282743b2c57f38985b3572113db3993..4399c1c9e40c1d0e87b34bdd6af19bdbb2bcaf72 100644
--- a/cc/ipc/begin_frame_args_struct_traits.h
+++ b/cc/ipc/begin_frame_args_struct_traits.h
@@ -7,6 +7,8 @@
 
 #include "cc/ipc/begin_frame_args.mojom-shared.h"
 #include "cc/output/begin_frame_args.h"
+#include "ipc/ipc_message_utils.h"
+#include "mojo/common/common_custom_types_struct_traits.h"
 
 namespace mojo {
 
@@ -56,6 +58,31 @@ struct StructTraits<cc::mojom::BeginFrameArgsDataView, cc::BeginFrameArgs> {
   }
 };
 
+template <>
+struct StructTraits<cc::mojom::BeginFrameAckDataView, cc::BeginFrameAck> {
+  static uint64_t sequence_number(const cc::BeginFrameAck& ack) {
+    return ack.sequence_number;
+  }
+
+  static uint64_t latest_confirmed_sequence_number(
+      const cc::BeginFrameAck& ack) {
+    return ack.latest_confirmed_sequence_number;
+  }
+
+  static uint32_t source_id(const cc::BeginFrameAck& ack) {
+    return ack.source_id;
+  }
+
+  static bool Read(cc::mojom::BeginFrameAckDataView data,
+                   cc::BeginFrameAck* out) {
+    out->source_id = data.source_id();
+    out->sequence_number = data.sequence_number();
+    out->latest_confirmed_sequence_number =
+        data.latest_confirmed_sequence_number();
+    return true;
+  }
+};
+
 }  // namespace mojo
 
 #endif  // CC_IPC_BEGIN_FRAME_ARGS_STRUCT_TRAITS_H_