Fix AddAccountSettings memory leak

The memory leak will always occur in AddAccoutSettings
when a null Bundle is returned in the addAccount we implement.

Bug: https://issuetracker.google.com/issues/65322371
Test: Install the app through the github i have offered in above link,
then press the "Test" item in ChooseAccountActivity (adb shell am start -n
'com.android.settings/.accounts.ChooseAccountActivity') serveal times.
Check the activity number by "adb shell dumpsys meminfo com.android.settings".

Change-Id: I3f139fe059e6094e9e5bf1660946ebc8bab6d090
Signed-off-by: tiansiming <tiansiming@xiaomi.com>
diff --git a/core/java/android/accounts/AccountManager.java b/core/java/android/accounts/AccountManager.java
index a446296..d22e268 100644
--- a/core/java/android/accounts/AccountManager.java
+++ b/core/java/android/accounts/AccountManager.java
@@ -2318,6 +2318,10 @@
         private class Response extends IAccountManagerResponse.Stub {
             @Override
             public void onResult(Bundle bundle) {
+                if (bundle == null) {
+                    onError(ERROR_CODE_INVALID_RESPONSE, "null bundle returned");
+                    return;
+                }
                 Intent intent = bundle.getParcelable(KEY_INTENT);
                 if (intent != null && mActivity != null) {
                     // since the user provided an Activity we will silently start intents