Add stub method isLockscreenLiveWallpaperEnabled() in qpr

Starting from U, this method returns a config boolean and serves as a flag to implement the new wallpaper logic.

In T, it is just a stub method that always return false.

Bug: 197814683
Test: treehugger (low-risk, no logic changes)
Change-Id: Iac70488c339629a474ad3bd50ae220dc18992e3d
Merged-In: I791ba72f571f996906d2c23f97bba7b88b2fe21f

core/java/android/app/WallpaperManager.java

@@ -752,6 +752,19 @@ public class WallpaperManager {
         return sGlobals.mService;
     }
 
+    /**
+     * Temporary method for project b/197814683
+     * Starting from U, this will return true if the new wallpaper logic is enabled,
+     * i.e. if the lockscreen wallpaper always uses a wallpaperService and not a static image.
+     * In T, this is just a stub method that always return false.
+     *
+     * @return false
+     * @hide
+     */
+    public boolean isLockscreenLiveWallpaperEnabled() {
+        return false;
+    }
+
     /**
      * Indicate whether wcg (Wide Color Gamut) should be enabled.
      * <p>