Fix b/6191707 Unable to set Custom wallpaper from Home

Change-Id: I130f74c94ebf5d93922807f7fee5ae7f189a15d4
diff --git a/src/com/android/gallery3d/app/AbstractGalleryActivity.java b/src/com/android/gallery3d/app/AbstractGalleryActivity.java
index 03f522f..9a1d3d3 100644
--- a/src/com/android/gallery3d/app/AbstractGalleryActivity.java
+++ b/src/com/android/gallery3d/app/AbstractGalleryActivity.java
@@ -43,6 +43,7 @@
     private static final String TAG = "AbstractGalleryActivity";
     private GLRootView mGLRootView;
     private StateManager mStateManager;
+    private GalleryActionBar mActionBar;
 
     private AlertDialog mAlertDialog = null;
     private BroadcastReceiver mMountReceiver = new BroadcastReceiver() {
@@ -192,7 +193,10 @@
 
     @Override
     public GalleryActionBar getGalleryActionBar() {
-        return null;
+        if (mActionBar == null) {
+            mActionBar = new GalleryActionBar(this);
+        }
+        return mActionBar;
     }
 
     @Override