Allow Workspace Scrim to be colored per state

Make it possible to set the color of workspace scrim to a different color
per state. Motivated by making Overview Scrim and All Apps scrims different
colors.

Bug: 186253733
Test: Local build and flash
Change-Id: Id7c38ce3c9173308eedfcb7592ececa7bd6bf220
diff --git a/src/com/android/launcher3/LauncherState.java b/src/com/android/launcher3/LauncherState.java
index 58df9c8..4c11725 100644
--- a/src/com/android/launcher3/LauncherState.java
+++ b/src/com/android/launcher3/LauncherState.java
@@ -30,6 +30,7 @@
 import static com.android.launcher3.testing.TestProtocol.SPRING_LOADED_STATE_ORDINAL;
 
 import android.content.Context;
+import android.graphics.Color;
 import android.view.animation.Interpolator;
 
 import com.android.launcher3.statemanager.BaseState;
@@ -217,8 +218,12 @@
         return 0;
     }
 
-    public float getWorkspaceScrimAlpha(Launcher launcher) {
-        return 0;
+    /**
+     * What color should the workspace scrim be in when at rest in this state.
+     * Return {@link Color#TRANSPARENT} for no scrim.
+     */
+    public int getWorkspaceScrimColor(Launcher launcher) {
+        return Color.TRANSPARENT;
     }
 
     /**