Introduce LauncherSearchCallback to handle search overlay status.

Bug: 20011047
Change-Id: I93cab4e0614b9658b4b657dd98dca68d42580e63
diff --git a/src/com/android/launcher3/LauncherCallbacks.java b/src/com/android/launcher3/LauncherCallbacks.java
index 0124d1f..a5f36ba 100644
--- a/src/com/android/launcher3/LauncherCallbacks.java
+++ b/src/com/android/launcher3/LauncherCallbacks.java
@@ -119,4 +119,11 @@
      */
     public void setLauncherAppsCallback(Object callbacks);
 
+    /**
+     * Sets the callbacks to allow reacting the actions of search overlays of the launcher.
+     *
+     * @param callbacks A set of callbacks to the Launcher, is actually a LauncherSearchCallback,
+     *                  but for implementation purposes is passed around as an object.
+     */
+    public void setLauncherSearchCallback(Object callbacks);
 }