修改UA string的默认值

有些运营商要求把特定信息加到UA中,例如需要把屏幕尺寸和CTC/2.0的信息加到UA中, 可以在这里加, 记录一下.

core/java/android/webkit/WebSettings.java

private synchronized String getCurrentUserAgent() {
        ...
        // add screen spec
        final String screenMetrics = getScreenMetrics();
        buffer.append("; ");
        buffer.append(screenMetrics);
        // add ctc spec info
        buffer.append("; ");
        buffer.append("CTC/2.0");
        ...
}

private String getScreenMetrics() {
    if(mWebView != null) {
                DisplayMetrics dm = mWebView.getContext().getResources().getDisplayMetrics();
                return String.format("%d*%d", dm.widthPixels, dm.heightPixels);
    } else {
                return "320*480"; //default screen metrics
    }
}