DO NOT MERGE Fixing some regressions

- Removing some legacy code with task loading
- Ensure that doze triggers are set correctly on configuration change
- Adding WCAGv2 contrast checking for deciding which foreground color to use for labels
- Bumping up the max thumbnail cache size slightly
- Fixing case where visibility state was not correct if you toggle recents too quickly

Change-Id: I5e954890d53948547842edce3c76c34d74e180a8
(cherry picked from commit e99e1009ce49caf220aa51c044ed53ac0a3b7cc6)
diff --git a/packages/SystemUI/src/com/android/systemui/recents/Constants.java b/packages/SystemUI/src/com/android/systemui/recents/Constants.java
index 8a80b76..e7ac2e1 100644
--- a/packages/SystemUI/src/com/android/systemui/recents/Constants.java
+++ b/packages/SystemUI/src/com/android/systemui/recents/Constants.java
@@ -32,7 +32,7 @@
             // Enables the filtering of tasks according to their grouping
             public static final boolean EnableTaskFiltering = false;
             // Enables clipping of tasks against each other
-            public static final boolean EnableTaskStackClipping = true;
+            public static final boolean EnableTaskStackClipping = false;
             // Enables tapping on the TaskBar to launch the task
             public static final boolean EnableTaskBarTouchEvents = true;
             // Enables app-info pane on long-pressing the icon