Fade out scrim when swiping to home

Bug: 134517106
Change-Id: Ica725e3a327c1c069e3859732ea6a878d361a3d8

src/com/android/launcher3/Workspace.java

@@ -1394,6 +1394,10 @@ public class Workspace extends PagedView<WorkspacePageIndicator>
         builder.play(stepAnimator);
     }
 
+    public WorkspaceStateTransitionAnimation getStateTransitionAnimation() {
+        return mStateTransitionAnimation;
+    }
+
     public void updateAccessibilityFlags() {
         // TODO: Update the accessibility flags appropriately when dragging.
         int accessibilityFlag = mLauncher.getStateManager().getState().workspaceAccessibilityFlag;

src/com/android/launcher3/WorkspaceStateTransitionAnimation.java

@@ -130,7 +130,10 @@ public class WorkspaceStateTransitionAnimation {
         propertySetter.setFloat(mWorkspace.getPageIndicator(), View.TRANSLATION_Y,
                 hotseatScaleAndTranslation.translationY, translationInterpolator);
 
-        // Set scrim
+        setScrim(propertySetter, state);
+    }
+
+    public void setScrim(PropertySetter propertySetter, LauncherState state) {
         WorkspaceAndHotseatScrim scrim = mLauncher.getDragLayer().getScrim();
         propertySetter.setFloat(scrim, SCRIM_PROGRESS, state.getWorkspaceScrimAlpha(mLauncher),
                 LINEAR);