Removing back-button alpha animation code

Back button is only animation in 2-button UI which is not supported anymore

Bug: 246006580
Test: Presubmit
Change-Id: I7385b07272e44c1f9f0488c158e1b4ee67060120
diff --git a/src/com/android/launcher3/LauncherState.java b/src/com/android/launcher3/LauncherState.java
index c3b5392..31a7d18 100644
--- a/src/com/android/launcher3/LauncherState.java
+++ b/src/com/android/launcher3/LauncherState.java
@@ -71,17 +71,14 @@
     public static final int FLAG_WORKSPACE_ICONS_CAN_BE_DRAGGED = BaseState.getFlag(2);
     // Flag to indicate that workspace should draw page background
     public static final int FLAG_WORKSPACE_HAS_BACKGROUNDS = BaseState.getFlag(3);
-    // True if the back button should be hidden when in this state (assuming no floating views are
-    // open, launcher has window focus, etc).
-    public static final int FLAG_HIDE_BACK_BUTTON = BaseState.getFlag(4);
     // Flag to indicate if the state would have scrim over sysui region: statu sbar and nav bar
-    public static final int FLAG_HAS_SYS_UI_SCRIM = BaseState.getFlag(5);
+    public static final int FLAG_HAS_SYS_UI_SCRIM = BaseState.getFlag(4);
     // Flag to inticate that all popups should be closed when this state is enabled.
-    public static final int FLAG_CLOSE_POPUPS = BaseState.getFlag(6);
-    public static final int FLAG_OVERVIEW_UI = BaseState.getFlag(7);
+    public static final int FLAG_CLOSE_POPUPS = BaseState.getFlag(5);
+    public static final int FLAG_OVERVIEW_UI = BaseState.getFlag(6);
 
     // Flag indicating that hotseat and its contents are not accessible.
-    public static final int FLAG_HOTSEAT_INACCESSIBLE = BaseState.getFlag(8);
+    public static final int FLAG_HOTSEAT_INACCESSIBLE = BaseState.getFlag(7);
 
 
     public static final float NO_OFFSET = 0;
@@ -110,8 +107,7 @@
      */
     public static final LauncherState NORMAL = new LauncherState(NORMAL_STATE_ORDINAL,
             LAUNCHER_STATE_HOME,
-            FLAG_DISABLE_RESTORE | FLAG_WORKSPACE_ICONS_CAN_BE_DRAGGED | FLAG_HIDE_BACK_BUTTON |
-                    FLAG_HAS_SYS_UI_SCRIM) {
+            FLAG_DISABLE_RESTORE | FLAG_WORKSPACE_ICONS_CAN_BE_DRAGGED | FLAG_HAS_SYS_UI_SCRIM) {
         @Override
         public int getTransitionDuration(Context context, boolean isToState) {
             // Arbitrary duration, when going to NORMAL we use the state we're coming from instead.