copy from mobile/android/app/assets/example_asset.txt
copy to mobile/android/bouncer/assets/example_asset.txt

--- a/mobile/android/bouncer/moz.build
+++ b/mobile/android/bouncer/moz.build
@@ -14,8 +14,12 @@ ANDROID_APK_NAME = 'bouncer'
 ANDROID_APK_PACKAGE = CONFIG['ANDROID_PACKAGE_NAME']
 
 # Putting branding earlier allows branders to override default resources.
 ANDROID_RES_DIRS += [
     '/' + CONFIG['MOZ_BRANDING_DIRECTORY'] + '/res', # For the icon.
     'res',
     '!/mobile/android/base/res', # For strings.
 ]
+
+ANDROID_ASSETS_DIRS += [
+    'assets',
+]