private Toolbar mToolbar;
    private WebFragment mWebFragment;

    private long mBeforeTime;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            SystemBarTintManager tintManager = new SystemBarTintManager(this);
            mToolbar = (Toolbar) findViewById(R.id.toolbar);
            tintManager.setStatusBarTintEnabled(true);
            setSupportActionBar(mToolbar);
            tintManager.setStatusBarTintResource(android.R.color.holo_blue_bright);
        }
        getSupportActionBar().setHomeButtonEnabled(true); //設定返回鍵可用
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }