Implement #8323587, #8323342, #8323590: new features.

8323587: Add feature for supporting app widgets
8323342: Add feature for replacing the home screen
8323590: Add feature for supporting input methods

The app widget service looks for the app widget feature
and refuses to work if it doesn't exist.  I didn't do
this for the input method service because some devices
will probably want to still make use of that mechanism
without supporting third party input methods.

Change-Id: Ie3b089105e104f4d767cdb03cdbe4fdb1c17382e

services/java/com/android/server/InputMethodManagerService.java

@@ -164,6 +164,7 @@ public class InputMethodManagerService extends IInputMethodManager.Stub
     final SettingsObserver mSettingsObserver;
     final IWindowManager mIWindowManager;
     final HandlerCaller mCaller;
+    final boolean mHasFeature;
     private InputMethodFileManager mFileManager;
     private InputMethodAndSubtypeListManager mImListManager;
     private final HardKeyboardListener mHardKeyboardListener;
@@ -608,6 +609,8 @@ public class InputMethodManagerService extends IInputMethodManager.Stub
         }, true /*asyncHandler*/);
         mWindowManagerService = windowManager;
         mHardKeyboardListener = new HardKeyboardListener();
+        mHasFeature = context.getPackageManager().hasSystemFeature(
+                PackageManager.FEATURE_INPUT_METHODS);
 
         mImeSwitcherNotification = new Notification();
         mImeSwitcherNotification.icon = com.android.internal.R.drawable.ic_notification_ime_default;