Remove WallpaperManagerCompat#getWallpaperId().

It is no longer necessary in the latest patch for color extraction.
(We call WallpaperManager#getWallpaperId() from Utilities instead.)

Change-Id: I9a9e5505e843674fcf3deaf3235fca1d1c6422d0
diff --git a/src/com/android/wallpaperpicker/common/WallpaperManagerCompat.java b/src/com/android/wallpaperpicker/common/WallpaperManagerCompat.java
index 92f24f2..96df749 100644
--- a/src/com/android/wallpaperpicker/common/WallpaperManagerCompat.java
+++ b/src/com/android/wallpaperpicker/common/WallpaperManagerCompat.java
@@ -30,6 +30,4 @@
             int whichWallpaper) throws IOException;
 
     public abstract void clear(int whichWallpaper) throws IOException;
-
-    public abstract int getWallpaperId(int whichWallpaper);
 }
diff --git a/src/com/android/wallpaperpicker/common/WallpaperManagerCompatV16.java b/src/com/android/wallpaperpicker/common/WallpaperManagerCompatV16.java
index ea3dc98..a320beb 100644
--- a/src/com/android/wallpaperpicker/common/WallpaperManagerCompatV16.java
+++ b/src/com/android/wallpaperpicker/common/WallpaperManagerCompatV16.java
@@ -24,9 +24,4 @@
     public void clear(int whichWallpaper) throws IOException {
         mWallpaperManager.clear();
     }
-
-    @Override
-    public int getWallpaperId(int whichWallpaper) {
-        return -1;
-    }
 }
diff --git a/src/com/android/wallpaperpicker/common/WallpaperManagerCompatVN.java b/src/com/android/wallpaperpicker/common/WallpaperManagerCompatVN.java
index d044d1f..2eb9c51 100644
--- a/src/com/android/wallpaperpicker/common/WallpaperManagerCompatVN.java
+++ b/src/com/android/wallpaperpicker/common/WallpaperManagerCompatVN.java
@@ -40,15 +40,4 @@
             super.clear(whichWallpaper);
         }
     }
-
-    @Override
-    public int getWallpaperId(int whichWallpaper) {
-        try {
-            // TODO: use mWallpaperManager.getWallpaperId(whichWallpaper) without reflection.
-            Method getWallpaperId = WallpaperManager.class.getMethod("getWallpaperId", int.class);
-            return (int) getWallpaperId.invoke(mWallpaperManager, whichWallpaper);
-        } catch (InvocationTargetException | NoSuchMethodException | IllegalAccessException e) {
-            return -1;
-        }
-    }
 }