Android 横屏时按键导航栏遮挡输入法窗口问题解决方案

最近遇到Android 6.0系统横屏时出现按键导航栏遮挡输入法窗口的问题，对比查看华为荣耀V9(Android 8.0）上也有同样的问题，如下图：

可见此问题是Android原生的Bug。其原因是由于导航栏在显示和隐藏的时候没有及时更新layout。
打印其堆栈信息如下：

修改PhoneWindow类的updateNavigationGuard方法，在updateNavigationGuard中调用requestFitSystemWindows方法请求一次新的layout。
文件位置： /frameworks/base/core/java/com/android/internal/policy/PhoneWindow.java

private void updateNavigationGuard(WindowInsets insets) {
    // IMEs lay out below the nav bar, but the content view must not (for back compat)
    if (getAttributes().type == WindowManager.LayoutParams.TYPE_INPUT_METHOD) {
        // prevent the content view from including the nav bar height
        if (mContentParent != null) {
            if (mContentParent.getLayoutParams() instanceof MarginLayoutParams) {
                MarginLayoutParams mlp =
                        (MarginLayoutParams) mContentParent.getLayoutParams();
                mlp.bottomMargin = insets.getSystemWindowInsetBottom();
                mContentParent.setLayoutParams(mlp);
            }
        }
        // position the navigation guard view, creating it if necessary
        if (mNavigationGuard == null) {
            mNavigationGuard = new View(mContext);
            mNavigationGuard.setBackgroundColor(mContext.getColor(
                    R.color.input_method_navigation_guard));
            addView(mNavigationGuard, indexOfChild(mNavigationColorViewState.view),
                    new LayoutParams(LayoutParams.MATCH_PARENT,
                            insets.getSystemWindowInsetBottom(),
                            Gravity.START | Gravity.BOTTOM));
        } else {
            LayoutParams lp = (LayoutParams) mNavigationGuard.getLayoutParams();
            lp.height = insets.getSystemWindowInsetBottom();
            mNavigationGuard.setLayoutParams(lp);
        }
        //add by pengtg begin.
        Log.d(TAG,"updateNavigationGuard+ insets " + insets);
        requestFitSystemWindows();
        //add by pengtg end.
    }
}