[Cronet] Use gn desc to find third party licenses on Android.

components/cronet/android/BUILD.gn

Index: components/cronet/android/BUILD.gn
diff --git a/components/cronet/android/BUILD.gn b/components/cronet/android/BUILD.gn
index 5e727a30ec2334c8460eadc04a43c913ec025f1e..42c1c4b4208410fcb13e0c20406fcbe36590b769 100644
--- a/components/cronet/android/BUILD.gn
+++ b/components/cronet/android/BUILD.gn
@@ -1185,13 +1185,17 @@ jar_src("jar_cronet_impl_native_java_source") {
 action("generate_licenses") {
   _license_path = "$_package_dir/LICENSE"
 
-  script = "//components/cronet/tools/cronet_licenses.py"
+  script = "//tools/licenses.py"
   outputs = [
     _license_path,
   ]
   args = [
-    "license",
+    "license_file",
     rebase_path(_license_path, root_build_dir),
+    "--gn-target",
+    "//components/cronet/android:cronet",
+    "--gn-out-dir",
+    ".",
   ]
 }