Add flag to disable customizing task transition animation.

    // trying to apply a new one.

    private static final boolean ALWAYS_KEEP_CURRENT = true;

    /**

     * Restrict ability of activities overriding transition animation in a way such that

     * an activity can do it only when the transition happens within a same task.

     *

     * @see android.app.Activity#overridePendingTransition(int, int)

     */

    private static final String DISABLE_CUSTOM_TASK_ANIMATION_PROPERTY =

            "persist.wm.disable_custom_task_animation";

    /**

     * @see #DISABLE_CUSTOM_TASK_ANIMATION_PROPERTY

     */

    static boolean sDisableCustomTaskAnimationProperty =

            SystemProperties.getBoolean(DISABLE_CUSTOM_TASK_ANIMATION_PROPERTY, false);

    private static final String DISABLE_TRIPLE_BUFFERING_PROPERTY =

            "ro.sf.disable_triple_buffer";