Tap the link below (user gesture required so DataSharingNavigationThrottle
intercepts the navigation). The t= access_token is 200 ASCII bytes
(≥128), so the serialized ReadGroupWithTokenParams length varint is
0xC8 0x01. ConvertUTF8ToJavaString() replaces the high-bit byte
with U+FFFD; Java-side parseFrom() throws InvalidProtocolBufferException; the
catch handler posts the native callback to a ThreadPool worker
(TaskTraits.USER_VISIBLE) instead of the UI thread.