Implements mojo::StrongBindingSet.

mojo/public/cpp/bindings/BUILD.gn

Index: mojo/public/cpp/bindings/BUILD.gn
diff --git a/mojo/public/cpp/bindings/BUILD.gn b/mojo/public/cpp/bindings/BUILD.gn
index c831ada7a4d74b7fb8570c943d41ba89043d4e3b..cbc20046d22942cfb65bb5db5aa5582505f6123a 100644
--- a/mojo/public/cpp/bindings/BUILD.gn
+++ b/mojo/public/cpp/bindings/BUILD.gn
@@ -124,6 +124,7 @@ component("bindings") {
     "pipe_control_message_handler.h",
     "pipe_control_message_handler_delegate.h",
     "pipe_control_message_proxy.h",
+    "raw_ptr_impl_ref_traits.h",
     "scoped_interface_endpoint_handle.h",
     "string_data_view.h",
     "string_traits.h",
@@ -132,6 +133,7 @@ component("bindings") {
     "string_traits_string_piece.h",
     "strong_associated_binding.h",
     "strong_binding.h",
+    "strong_binding_set.h",
     "struct_ptr.h",
     "sync_call_restrictions.h",
     "sync_handle_registry.h",
@@ -139,6 +141,7 @@ component("bindings") {
     "thread_safe_interface_ptr.h",
     "type_converter.h",
     "union_traits.h",
+    "unique_ptr_impl_ref_traits.h",
   ]
 
   public_deps = [