Add API to clear a specific wallpaper

There was previously no public API for clearing the keyguard wallpaper
versus the system wallpaper, or both.  Now there is.

Bug 27400185

Change-Id: If1789dd430040acdf16d77413c0e4b46bf3789f3
diff --git a/api/current.txt b/api/current.txt
index aeaae55..8624cf6 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -5711,6 +5711,7 @@
 
   public class WallpaperManager {
     method public void clear() throws java.io.IOException;
+    method public void clear(int) throws java.io.IOException;
     method public void clearWallpaperOffsets(android.os.IBinder);
     method public void forgetLoadedWallpaper();
     method public android.graphics.drawable.Drawable getBuiltInDrawable();
diff --git a/api/system-current.txt b/api/system-current.txt
index 1a2c854..505b1fb 100644
--- a/api/system-current.txt
+++ b/api/system-current.txt
@@ -5843,6 +5843,7 @@
 
   public class WallpaperManager {
     method public void clear() throws java.io.IOException;
+    method public void clear(int) throws java.io.IOException;
     method public void clearWallpaper();
     method public void clearWallpaper(int, int);
     method public void clearWallpaperOffsets(android.os.IBinder);
diff --git a/api/test-current.txt b/api/test-current.txt
index 1039fed..3c54b34 100644
--- a/api/test-current.txt
+++ b/api/test-current.txt
@@ -5715,6 +5715,7 @@
 
   public class WallpaperManager {
     method public void clear() throws java.io.IOException;
+    method public void clear(int) throws java.io.IOException;
     method public void clearWallpaperOffsets(android.os.IBinder);
     method public void forgetLoadedWallpaper();
     method public android.graphics.drawable.Drawable getBuiltInDrawable();
diff --git a/core/java/android/app/WallpaperManager.java b/core/java/android/app/WallpaperManager.java
index 4d8d96b0..6bc03f7 100644
--- a/core/java/android/app/WallpaperManager.java
+++ b/core/java/android/app/WallpaperManager.java
@@ -1433,6 +1433,25 @@
     }
 
     /**
+     * Remove one or more currently set wallpapers, reverting to the system default
+     * display for each one.  If {@link #FLAG_SET_SYSTEM} is set in the {@code which}
+     * parameter, the intent {@link Intent#ACTION_WALLPAPER_CHANGED} will be broadcast
+     * upon success.
+     *
+     * @param which A bitwise combination of {@link #FLAG_SET_SYSTEM} or
+     *   {@link #FLAG_SET_LOCK}
+     * @throws IOException If an error occurs reverting to the built-in wallpaper.
+     */
+    public void clear(int which) throws IOException {
+        if ((which & FLAG_SET_SYSTEM) != 0) {
+            clear();
+        }
+        if ((which & FLAG_SET_LOCK) != 0) {
+            clearWallpaper(FLAG_SET_LOCK, mContext.getUserId());
+        }
+    }
+
+    /**
      * Open stream representing the default static image wallpaper.
      *
      * @hide
diff --git a/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java b/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java
index ba0d340..a0a971a 100644
--- a/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java
+++ b/services/core/java/com/android/server/wallpaper/WallpaperManagerService.java
@@ -882,6 +882,9 @@
             wallpaper = mLockWallpaperMap.get(userId);
             if (wallpaper == null) {
                 // It's already gone; we're done.
+                if (DEBUG) {
+                    Slog.i(TAG, "Lock wallpaper already cleared");
+                }
                 return;
             }
         } else {
@@ -902,14 +905,19 @@
                 wallpaper.wallpaperFile.delete();
                 wallpaper.cropFile.delete();
                 if (which == FLAG_SET_LOCK) {
+                    mLockWallpaperMap.remove(userId);
                     final IWallpaperManagerCallback cb = mKeyguardListener;
                     if (cb != null) {
+                        if (DEBUG) {
+                            Slog.i(TAG, "Notifying keyguard of lock wallpaper clear");
+                        }
                         try {
                             cb.onWallpaperChanged();
                         } catch (RemoteException e) {
                             // Oh well it went away; no big deal
                         }
                     }
+                    saveSettingsLocked(userId);
                     return;
                 }
             }