Settings ChooseLockscreen* dismiss in background.

Whenever launching
ChooseLockGeneric/ChooseLockPassword/ChooseLockPassword the activity
will finish itself when it goes into the background. This is to ensure
that a user only has an opporunity to complete this process once the
activity is shown. (It cannot be resumed after a power button press, or
sending the activity to the background)

Test: Verified in Settings that the ChooseLockGeneric,
ChooseLockPassword and the ChooseLockPattern activities now exit if they
are sent to the background.
Test: Same as above but in SUW
Test: m -j40 RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.password.ChooseLockPatternTest
Test: m -j40 RunSettingsRoboTests ROBOTEST_FILTER=com.android.settings.password.ChooseLockPasswordTest
Fixes: 287473148

Change-Id: Icc9142ff4672ab3669b2f425ff351b03ce7a223a

src/com/android/settings/password/ChooseLockPassword.java

@@ -219,6 +219,13 @@ public class ChooseLockPassword extends SettingsActivity {
         findViewById(R.id.content_parent).setFitsSystemWindows(false);
         getWindow().addFlags(WindowManager.LayoutParams.FLAG_SECURE);
     }
+    @Override
+    public void onPause() {
+        super.onPause();
+        if (!isChangingConfigurations()) {
+            finish();
+        }
+    }
 
     public static class ChooseLockPasswordFragment extends InstrumentedFragment
             implements OnEditorActionListener, TextWatcher, SaveAndFinishWorker.Listener {