Introduce default value to fixed to user rotation.

The default value is calculated based on if it's PC and if it's forced
desktop mode for external displays.

Bug: 124420570
Test: WmTests pass. Manual tests.
Change-Id: I28148e0e2fb041a862eefd1b8969b3fae58b7ed4
diff --git a/services/tests/wmtests/src/com/android/server/wm/DisplayContentTests.java b/services/tests/wmtests/src/com/android/server/wm/DisplayContentTests.java
index b1b8e8c..69f7ced 100644
--- a/services/tests/wmtests/src/com/android/server/wm/DisplayContentTests.java
+++ b/services/tests/wmtests/src/com/android/server/wm/DisplayContentTests.java
@@ -621,7 +621,8 @@
     @Test
     public void testOnDescendantOrientationRequestChanged_FrozenToUserRotation() {
         final DisplayContent dc = createNewDisplay();
-        dc.getDisplayRotation().setFixedToUserRotation(true);
+        dc.getDisplayRotation().setFixedToUserRotation(
+                DisplayRotation.FIXED_TO_USER_ROTATION_ENABLED);
         mWm.mAtmService.mRootActivityContainer = mock(RootActivityContainer.class);
         final int newOrientation = dc.getLastOrientation() == SCREEN_ORIENTATION_LANDSCAPE
                 ? SCREEN_ORIENTATION_PORTRAIT