Set REQUIRE_PASSWORD_TO_DECRYPT to false when insecure screen lock is
enabled

Some users run into a problem when choosing a secure screen lock with
accessiblity enabled that they will not be warned the screen lock may
not be available when they unlock their devices. One cause is
REQUIRE_PASSWORD_TO_DECRYPT is not set back to false when users choose
to use an insecure lock screen. So when they decide to change back to a
secure screen lock, the warning message will not be shown.

Bug: 18799150
Change-Id: I52bdc93e7a5ce3c4f7715057c73b4de280b443f6
diff --git a/core/java/com/android/internal/widget/LockPatternUtils.java b/core/java/com/android/internal/widget/LockPatternUtils.java
index 123d1ac..aa60eba 100644
--- a/core/java/com/android/internal/widget/LockPatternUtils.java
+++ b/core/java/com/android/internal/widget/LockPatternUtils.java
@@ -472,6 +472,8 @@
             updateEncryptionPassword(StorageManager.CRYPT_TYPE_DEFAULT, null);
         }
 
+        setCredentialRequiredToDecrypt(false);
+
         getDevicePolicyManager().setActivePasswordState(
                 DevicePolicyManager.PASSWORD_QUALITY_UNSPECIFIED, 0, 0, 0, 0, 0, 0, 0, userHandle);