Add alpha animation for 180 rotation

Fixes: 160161214
Test: Rotate device with 180 degree and check there is no
      obvious jump cut.
Change-Id: I6fb195edd580e0e07d3feea8b52079342213646d
diff --git a/core/res/res/anim/screen_rotate_180_enter.xml b/core/res/res/anim/screen_rotate_180_enter.xml
index 889a615..3b6b407 100644
--- a/core/res/res/anim/screen_rotate_180_enter.xml
+++ b/core/res/res/anim/screen_rotate_180_enter.xml
@@ -25,4 +25,10 @@
         android:fillBefore="true" android:fillAfter="true"
         android:interpolator="@interpolator/fast_out_slow_in"
         android:duration="@android:integer/config_screen_rotation_total_180" />
+    <alpha android:fromAlpha="0.0" android:toAlpha="1.0"
+        android:fillEnabled="true"
+        android:fillBefore="true" android:fillAfter="true"
+        android:interpolator="@interpolator/screen_rotation_alpha_in"
+        android:startOffset="@android:integer/config_screen_rotation_fade_in_delay"
+        android:duration="@android:integer/config_screen_rotation_fade_in" />
 </set>
diff --git a/core/res/res/anim/screen_rotate_180_exit.xml b/core/res/res/anim/screen_rotate_180_exit.xml
index 766fcfa..26fb6d8 100644
--- a/core/res/res/anim/screen_rotate_180_exit.xml
+++ b/core/res/res/anim/screen_rotate_180_exit.xml
@@ -25,4 +25,9 @@
         android:fillBefore="true" android:fillAfter="true"
         android:interpolator="@interpolator/fast_out_slow_in"
         android:duration="@android:integer/config_screen_rotation_total_180" />
-</set>
\ No newline at end of file
+    <alpha android:fromAlpha="1.0" android:toAlpha="0.0"
+        android:fillEnabled="true"
+        android:fillBefore="true" android:fillAfter="true"
+        android:interpolator="@interpolator/screen_rotation_alpha_out"
+        android:duration="@android:integer/config_screen_rotation_fade_out" />
+</set>