[unification] Move //zircon/system/ulib/utf_conversion to the GN build

Affected libraries:
//zircon/system/ulib/utf_conversion

Generated with //scripts/unification/move_cpp_library.py

Bug: 36548
Change-Id: Ife901c5395a1ca55d8124f261025e2894f20c7eb
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/378143
Reviewed-by: P.Y. Laligand <pylaligand@google.com>
Commit-Queue: Theodore Dubois <tbodt@google.com>
diff --git a/src/devices/usb/drivers/usb-bus/BUILD.gn b/src/devices/usb/drivers/usb-bus/BUILD.gn
index cff328b..c1b3a57 100644
--- a/src/devices/usb/drivers/usb-bus/BUILD.gn
+++ b/src/devices/usb/drivers/usb-bus/BUILD.gn
@@ -28,8 +28,8 @@
     "//sdk/banjo/ddk.protocol.usb.hub",
     "//zircon/public/lib/ddk",
     "//zircon/public/lib/fbl",
-    "//zircon/public/lib/utf_conversion",
     "//zircon/system/banjo/ddk.protocol.usb.composite",
+    "//zircon/system/ulib/utf_conversion",
   ]
   public_deps = [
     "//sdk/banjo/ddk.protocol.usb.bus",
@@ -68,8 +68,8 @@
     ":common",
     "//zircon/public/lib/fake-bti",
     "//zircon/public/lib/fake_ddk",
-    "//zircon/public/lib/utf_conversion",
     "//zircon/public/lib/zxtest",
+    "//zircon/system/ulib/utf_conversion",
   ]
 }
 
diff --git a/zircon/system/ulib/BUILD.gn b/zircon/system/ulib/BUILD.gn
index 9ea9773..4f31424 100644
--- a/zircon/system/ulib/BUILD.gn
+++ b/zircon/system/ulib/BUILD.gn
@@ -501,7 +501,6 @@
 #------------------
 #------------------
 #------------------
-    "utf_conversion",
 #------------------
 #------------------
     "vdso-code-header",
diff --git a/zircon/system/ulib/utf_conversion/BUILD.gn b/zircon/system/ulib/utf_conversion/BUILD.gn
index a79fb62..c18ea69 100644
--- a/zircon/system/ulib/utf_conversion/BUILD.gn
+++ b/zircon/system/ulib/utf_conversion/BUILD.gn
@@ -1,9 +1,23 @@
 # Copyright 2019 The Fuchsia Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
+
+##########################################
+# Though under //zircon, this build file #
+# is meant to be used in the Fuchsia GN  #
+# build.                                 #
+# See fxb/36548.                         #
+##########################################
+
+assert(!defined(zx) || zx != "/",
+       "This file can only be used in the Fuchsia GN build.")
+
+import("//build/unification/zx_library.gni")
+
+
 zx_library("utf_conversion") {
   sdk = "static"
   sdk_headers = [ "utf_conversion/utf_conversion.h" ]
   sources = [ "utf_conversion.cc" ]
-  deps = [ "$zx/system/ulib/fbl" ]
+  deps = [ "//zircon/public/lib/fbl" ]
 }
diff --git a/zircon/system/ulib/utf_conversion/test/BUILD.gn b/zircon/system/ulib/utf_conversion/test/BUILD.gn
index 0a057d5..939c8e3 100644
--- a/zircon/system/ulib/utf_conversion/test/BUILD.gn
+++ b/zircon/system/ulib/utf_conversion/test/BUILD.gn
@@ -39,14 +39,14 @@
     "//zircon/public/lib/fbl",
     "//zircon/public/lib/fdio",
     "//zircon/public/lib/pretty",
-    "//zircon/public/lib/utf_conversion",
     "//zircon/public/lib/zxtest",
+    "//zircon/system/ulib/utf_conversion",
   ]
 }
 
 fuzzer("utf_conversion-fuzzer") {
   sources = [ "utf_conversion-fuzzer.cc" ]
-  deps = [ "//zircon/public/lib/utf_conversion" ]
+  deps = [ "//zircon/system/ulib/utf_conversion" ]
 }
 
 unittest_package("utf-conversion-package") {