How can I find the messaging sounds that are used in Google's Messenger (sms) app? I am trying to find the "message sent" "blip" sound specifically
AOSP: The AOSP Messages source code is here, but the source code does not have a "sent sound" (nor any sound) because those sounds are in your system sounds. You can find them at /system/media/ from a file manager like ES File Explorer.

New Google Messenger: The sounds can be found by decompressing the .apk. They are in /com.google.android.apps.messaging/res/raw/. All independent sounds are there!