Support gray hotseat background in all apps transition
b/30201515

Change-Id: Ie4b8442ac804b4df94e9673608129e6ffc0c3360
diff --git a/src/com/android/launcher3/Hotseat.java b/src/com/android/launcher3/Hotseat.java
index b75d2c0..7e2b42e 100644
--- a/src/com/android/launcher3/Hotseat.java
+++ b/src/com/android/launcher3/Hotseat.java
@@ -23,6 +23,7 @@
 import android.graphics.Rect;
 import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
+import android.support.v4.graphics.ColorUtils;
 import android.util.AttributeSet;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
@@ -67,7 +68,9 @@
         super(context, attrs, defStyle);
         mLauncher = (Launcher) context;
         mHasVerticalHotseat = mLauncher.getDeviceProfile().isVerticalBarLayout();
-        mBackground = new ColorDrawable();
+        mBackgroundColor = ColorUtils.setAlphaComponent(
+                context.getColor(R.color.all_apps_container_color), 0);
+        mBackground = new ColorDrawable(mBackgroundColor);
         setBackground(mBackground);
     }
 
@@ -227,7 +230,7 @@
         }
     }
 
-    public int getBackgroundDrawableAlpha() {
-        return Color.alpha(mBackgroundColor);
+    public int getBackgroundDrawableColor() {
+        return mBackgroundColor;
     }
 }