gn2bp: Add "android_jar.classes" to jni_generator genrules

This is a necessary file for the jni_generator.py to function.

Test: m cronet_aml_net_net
Change-Id: I4d9d81ee65efdd4e01da57048212664bb3069387
diff --git a/tools/gn2bp/gen_android_bp b/tools/gn2bp/gen_android_bp
index aa7cdd8..dac96f0 100755
--- a/tools/gn2bp/gen_android_bp
+++ b/tools/gn2bp/gen_android_bp
@@ -950,6 +950,10 @@
     module.genrule_headers.add(header_module.name)
     module.genrule_srcs.add(':' + module.name)
     blueprint.add_module(header_module)
+  elif target.script == "//base/android/jni_generator/jni_generator.py":
+    # android_jar.classes should be part of the tools as it list implicit classes
+    # for the script to generate JNI headers.
+    module.tool_files.add("base/android/jni_generator/android_jar.classes")
 
   blueprint.add_module(module)
   return module