Create a basic doze dream in SystemUI.

The doze dream is not configured by default.

When configured, the doze dream does not show anything by default.
It teases a dark version of the keyguard (showing only the time
and notifications) when a notification arrives or significant motion
is detected.

Bug:15863249
Change-Id: Icfceb054d35d6fd4d9178eda7480e2464873ca4b
diff --git a/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java b/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java
index fcc951e..0582140 100644
--- a/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java
+++ b/packages/SystemUI/src/com/android/systemui/statusbar/stack/AmbientState.java
@@ -33,6 +33,7 @@
     private float mOverScrollBottomAmount;
     private int mSpeedBumpIndex = -1;
     private float mScrimAmount;
+    private boolean mDark;
 
     public int getScrollY() {
         return mScrollY;
@@ -62,6 +63,11 @@
         mDimmed = dimmed;
     }
 
+    /** In dark mode, we draw as little as possible, assuming a black background */
+    public void setDark(boolean dark) {
+        mDark = dark;
+    }
+
     /**
      * In dimmed mode, a child can be activated, which happens on the first tap of the double-tap
      * interaction. This child is then scaled normally and its background is fully opaque.
@@ -74,6 +80,10 @@
         return mDimmed;
     }
 
+    public boolean isDark() {
+        return mDark;
+    }
+
     public ActivatableNotificationView getActivatedChild() {
         return mActivatedChild;
     }