Return AuthenticationCallback results on the UI thread (if the AT/ATS call was invoked there)

[iambmelt]

See issue raised by #1076

This PR does not fix the issue, but adds logging to accompany newly created test cases for this problem.

Edit - PR has been updated to resolve #1076 (see commit ae859af)

Interactive Auth w/o Broker | AuthenticationCallback returns on UI Thread - Test Case 345978
Interactive Auth w/  Broker | AuthenticationCallback returns on UI Thread - Test Case 345980
Silent Auth w/o Broker      | AuthenticationCallback returns on UI Thread - Test Case 345991
Silent Auth w/  Broker      | AuthenticationCallback returns on UI Thread - Test Case 346012

[piqiums]

furthermore, in the method body of "showMessage", could we use something similar to:
runOnUiThread(new Runnable() {
@OverRide
public void run() {
Toast.makeText(MainActivity.this, msg, Toast.LENGTH_LONG).show();
}
});

thanks

[heidijinxujia]

Thanks a lot for the repro and the detailed test cases. These are super helpful. Currently, it seems to be a 100% repro bug on Callback and we definitely need to deliver a fix before more customers encountering this issue.

Just an open suggestion, as we are not going to merge this PR into the release branch. I think it could be better to add the fix of this issue, like using "runOnUiThread" besides logging.

I will leave the priority to @nazukj and @addev-ashish .

[iambmelt]

@heidijinxujia @piqiums See commit ae859af

This commit conditionally creates the CallbackHandler on the UI thread if acquireToken or acquireTokenSilent was called on it.

[iambmelt]

Relevant: #888 #906

[iambmelt]

Alternatively, if the memory issue is a concern, we could consider running the following implementation through the tests and seeing how it fares

private static Handler mUiThreadHandler;
private static Handler mBackgroundHandler;

private static Handler mUiThreadHandler;
    private static Handler mBackgroundHandler;

    private synchronized Handler getHandler() {
        final Handler handler;

        if (onUiThread()) {
            if (null == mUiThreadHandler) {
                // Callback should be invoked on the UI thread.
                mUiThreadHandler = new Handler(Looper.getMainLooper());
            }

            Logger.v(TAG, "Using UI thread Handler.");
            handler = mUiThreadHandler;
        } else {
            if (null == mBackgroundHandler) {
                // We're on a background thread, so the handler can be anything...
                HandlerThread acquireTokenHandlerThread = new HandlerThread("AcquireTokenRequestHandlerThread");
                acquireTokenHandlerThread.start();
                mBackgroundHandler = new Handler(acquireTokenHandlerThread.getLooper());
            }

            Logger.v(TAG, "Using arbitrary thread Handler.");
            handler = mBackgroundHandler;
        }

        return handler;
    }

[iambmelt]

Not a priority right now - no cycles to run stress test.

Closing.