Prevent all apps transition NPE

b/29643291
b/29642263

> Also do not change status bar when landscape mode

Change-Id: I1e44af8e031856a50a7413ad297c437245e8b2aa
diff --git a/src/com/android/launcher3/Hotseat.java b/src/com/android/launcher3/Hotseat.java
index 5245509..b2f24be 100644
--- a/src/com/android/launcher3/Hotseat.java
+++ b/src/com/android/launcher3/Hotseat.java
@@ -227,4 +227,8 @@
             setBackground(mBackground);
         }
     }
+
+    public int getBackgroundDrawableAlpha() {
+        return Color.alpha(mBackgroundColor);
+    }
 }