Merge "Add API comment for new API in WallpaperService."

api/current.txt

@@ -42134,7 +42134,7 @@ package android.service.wallpaper {
     method protected void dump(String, java.io.FileDescriptor, java.io.PrintWriter, String[]);
     method public int getDesiredMinimumHeight();
     method public int getDesiredMinimumWidth();
-    method public android.content.Context getDisplayContext();
+    method @Nullable public android.content.Context getDisplayContext();
     method public android.view.SurfaceHolder getSurfaceHolder();
     method public boolean isPreview();
     method public boolean isVisible();

core/java/android/app/WallpaperInfo.java

@@ -371,10 +371,17 @@ public final class WallpaperInfo implements Parcelable {
      * Returns whether this wallpaper service can support multiple engines to render on each surface
      * independently. An example use case is a multi-display set-up where the wallpaper service can
      * render surfaces to each of the connected displays.
+     * <p>
+     * This corresponds to the value {@link android.R.styleable#Wallpaper_supportsMultipleDisplays}
+     * in the XML description of the wallpaper.
+     * <p>
+     * The default value is {@code false}.
      *
      * @see WallpaperService#onCreateEngine()
      * @see WallpaperService.Engine#onCreate(SurfaceHolder)
      * @return {@code true} if multiple engines can render independently on each surface.
+     *
+     * @attr ref android.R.styleable#Wallpaper_supportsMultipleDisplays
      */
     public boolean supportsMultipleDisplays() {
         return mSupportMultipleDisplays;

core/java/android/service/wallpaper/WallpaperService.java

@@ -1068,9 +1068,13 @@ public abstract class WallpaperService extends Service {
          * For multiple display environment, multiple engines can be created to render on each
          * display, but these displays may have different densities. Use this context to get the
          * corresponding resources for currently display, avoiding the context of the service.
+         * <p>
+         * The display context will never be {@code null} after
+         * {@link Engine#onCreate(SurfaceHolder)} has been called.
          *
          * @return A {@link Context} for current display.
          */
+        @Nullable
         public Context getDisplayContext() {
             return mDisplayContext;
         }

core/res/res/values/attrs.xml

@@ -8004,7 +8004,8 @@
 
         <!-- Indicates that this wallpaper service can support multiple engines to render on each
              surface independently. An example use case is a multi-display set-up where the
-             wallpaper service can render surfaces to each of the connected displays. -->
+             wallpaper service can render surfaces to each of the connected displays. Corresponds to
+             {@link android.app.WallpaperInfo#supportsMultipleDisplays()} -->
         <attr name="supportsMultipleDisplays" format="boolean" />
 
     </declare-styleable>