Adds BeginFrameControl via DevTools.

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..a509a7dc0e0fec5c4f025925cc917cb25877aa53 100644
--- a/cc/ipc/begin_frame_args_struct_traits.h
+++ b/cc/ipc/begin_frame_args_struct_traits.h
@@ -32,6 +32,10 @@ struct StructTraits<cc::mojom::BeginFrameArgsDataView, cc::BeginFrameArgs> {
     return args.on_critical_path;
   }
 
+  static bool allow_latency_optimizations(const cc::BeginFrameArgs& args) {
+    return args.allow_latency_optimizations;
+  }
+
   static bool Read(cc::mojom::BeginFrameArgsDataView data,
                    cc::BeginFrameArgs* out) {
     if (!data.ReadFrameTime(&out->frame_time) ||
@@ -42,6 +46,7 @@ struct StructTraits<cc::mojom::BeginFrameArgsDataView, cc::BeginFrameArgs> {
     out->type =
         static_cast<cc::BeginFrameArgs::BeginFrameArgsType>(data.type());
     out->on_critical_path = data.on_critical_path();
+    out->allow_latency_optimizations = data.allow_latency_optimizations();
     return true;
   }
 };