Adds the ability for Launcher3 to respond to QSB alpha change requests.

Test: Tested locally
BUG:124063782
Change-Id: I8c4bfaa62d9608fcfffff5e30b2913f3a6fb2f75
(cherry picked from commit 827f0807d3d7c92874541b540350e53a0a434e19)
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index 89236aa..f8d9959 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -408,6 +408,13 @@
         onIdpChanged(idp);
     }
 
+    public void setQuickSearchBarAlpha(float alpha) {
+        View qsbAllApps = findViewById(R.id.search_container_all_apps);
+        if (qsbAllApps != null) {
+            qsbAllApps.setAlpha(alpha);
+        }
+    }
+
     private void onIdpChanged(InvariantDeviceProfile idp) {
         mUserEventDispatcher = null;