Memory leaks: field c hangs onto a Context reference; and CallbackContext is leaked from within AFKeyStore

[markproxy]

Report

Plugin Version

6.5.2

On what Platform are you having the issue?

android

What did you do?

Used Leak Canary to monitor for leaks in an application that uses this plugin, and found two leaks.

What did you expect to happen?

No leaks

What happened instead?

I tracked down two different leaks:

• The field c hangs onto a Context reference; this is easily fixed by using a local variable instead
• I discovered that a class within AppsFlyer lib (AFKeyStore) fails to release its reference to the plugin's AppsFlyerRequestListener, so we need to wrap AppsFlyerRequestListener's reference to CallbackContext in a WeakReference so that it can be garbage-collected, along with its web view and associated activity

Please provide any other relevant information.

I found these leaks in an earlier version of the plugin, but I see in code that they still exist.

[markproxy]

I have fixes for both of these leaks, and I plan to share them in a PR.

[markproxy]

PR: #200