Correctly initialize rotation animation hint.

In the case of no activity options we won't initialize
it again later, and so we will override the apps request
with a hint of 0 (ROTATION_ANIMATION_ROTATE).

Bug: 30683604
Change-Id: I5eed12adfbb241859503bcd40f15ee82141436d8

services/core/java/com/android/server/am/ActivityRecord.java

@@ -221,7 +221,12 @@ final class ActivityRecord {
     boolean pendingVoiceInteractionStart;   // Waiting for activity-invoked voice session
     IVoiceInteractionSession voiceSession;  // Voice interaction session for this activity
 
-    int mRotationAnimationHint;
+    // A hint to override the window specified rotation animation, or -1
+    // to use the window specified value. We use this so that
+    // we can select the right animation in the cases of starting
+    // windows, where the app hasn't had time to set a value
+    // on the window.
+    int mRotationAnimationHint = -1;
 
     private static String startingWindowStateToString(int state) {
         switch (state) {