Make sample IME aware of language switching

This CL demonstrates how the new language switching functionality
should work by using the SoftKeyboard sample.

BUG: 15267645
Change-Id: I18ab25a0784979fe6028b97a22ff02bfd502d506

samples/SoftKeyboard/src/com/example/android/softkeyboard/LatinKeyboardView.java

@@ -26,6 +26,8 @@ import android.view.inputmethod.InputMethodSubtype;
 public class LatinKeyboardView extends KeyboardView {
 
     static final int KEYCODE_OPTIONS = -100;
+    // TODO: Move this into android.inputmethodservice.Keyboard
+    static final int KEYCODE_LANGUAGE_SWITCH = -101;
 
     public LatinKeyboardView(Context context, AttributeSet attrs) {
         super(context, attrs);