gn2bp: Use python3 for jni_registration_generator.py

Test: ./update_results.sh
Change-Id: If3d694d32b3396404b48e045c7a6163d934f8129
diff --git a/tools/gn2bp/Android.bp.swp b/tools/gn2bp/Android.bp.swp
index e13e2f8..247d896 100644
--- a/tools/gn2bp/Android.bp.swp
+++ b/tools/gn2bp/Android.bp.swp
@@ -1968,7 +1968,7 @@
          "do " +
          "echo \"../$$current_dir/$$f\" >> $(genDir)/java.sources; " +
          "done; " +
-         "$(location base/android/jni_generator/jni_registration_generator.py) --srcjar-path " +
+         "python3 $(location base/android/jni_generator/jni_registration_generator.py) --srcjar-path " +
          "$(genDir)/components/cronet/android/cronet_jni_registration.srcjar " +
          "--depfile " +
          "$(genDir)/components/cronet/android/cronet_jni_registration.d " +
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index b7c8b88..d06f215 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -988,6 +988,8 @@
     # for the script to generate JNI headers.
     module.tool_files.add("base/android/jni_generator/android_jar.classes")
   elif target.script == '//base/android/jni_generator/jni_registration_generator.py':
+    # jni_registration_generator.py doesn't work with python2
+    module.cmd = "python3 " + module.cmd
     # Path in the original sources file does not work in genrule.
     # So creating sources file in cmd based on the srcs of this target.
     # Adding ../$(current_dir)/ to the head because jni_registration_generator.py uses the files