[Android] New Embedding API

This commit implements onCreateWindowRequested of XWalkView
Also fixed the type error when generating some wrapper interface
Good point.
Indeed, there's a lot of handles around setNewContents in WebView. The impl of AwContents is like below:

        if (wasFocused) onFocusChanged(false, 0, null);
        if (wasWindowFocused) onWindowFocusChanged(false);
        if (wasViewVisible) setViewVisibilityInternal(false);
        if (wasWindowVisible) setWindowVisibilityInternal(false);
        if (wasAttached) onDetachedFromWindow();
        if (!wasPaused) onPause();

        setNewAwContents(popupNativeAwContents);

        if (!wasPaused) onResume();
        if (wasAttached) {
            onAttachedToWindow();
            postInvalidateOnAnimation();
        }
        onSizeChanged(mContainerView.getWidth(), mContainerView.getHeight(), 0, 0);
        if (wasWindowVisible) setWindowVisibilityInternal(true);
        if (wasViewVisible) setViewVisibilityInternal(true);
        if (wasWindowFocused) onWindowFocusChanged(wasWindowFocused);
        if (wasFocused) onFocusChanged(true, 0, null);

Most of these handles is not implemented in XWalkContent yet, and some impl will need BrowserViewRenderer, which using SynchronousCompositor that cannot be used in XWalkView. And even in AwContents, it doesn't check the status of parent's window, only care itself's.

For the suspending things before setNewAwContents, because the instance is allways the new created XWalkView and the window status is quite initial, I'm not sure all of these is really necessary to XWalkView in this case.

Among the handles after setNewAwContents, the critical one is to call onResume() otherwise the new contents will not shown.

Currently, simplifying things may be most efficient. I'm supposed to do more impl if I realized anything in the future or something not ok in actual usage