How to using UniWebView2 (UniWebView2の使用方法) ref: http://qiita.com/TomoakiNagahara/items/2785c85c7b416f88e08f

file0.cs

using UnityEngine;
using System.Collections;

public class Main : MonoBehaviour {

    private UniWebView _webView;
    private string _errorMessage;

    // Use this for initialization
    void Start () {
        Debug.Log (this._errorMessage);

        _webView = GetComponent<UniWebView>();
        if (_webView == null) {

            //  User agent masquerade.
            UniWebView.SetUserAgent ("Mozilla/5.0 (iPhone; CPU iPhone OS 8_0 like Mac OS X) AppleWebKit/600.1.4 (KHTML, like Gecko) Version/8.0 Mobile/12A365 Safari/600.1.4");

            _webView = gameObject.AddComponent<UniWebView>();
            _webView.OnReceivedMessage += OnReceivedMessage;
            _webView.OnLoadComplete += OnLoadComplete;
            _webView.OnWebViewShouldClose += OnWebViewShouldClose;
            _webView.OnEvalJavaScriptFinished += OnEvalJavaScriptFinished;
            _webView.InsetsForScreenOreitation += InsetsForScreenOreitation;
        }
        _webView.url = "https://uqunie.com/useragent";
        _webView.Load();
        _webView.Show ();
        _errorMessage = null;
    }

    void OnLoadComplete(UniWebView webView, bool success, string errorMessage) {
        if (success) {
            webView.Show();
        } else {
            Debug.Log("Something wrong in webview loading: " + errorMessage);
            _errorMessage = errorMessage;
        }
    }

    bool OnWebViewShouldClose(UniWebView webView) {
        if (webView == _webView) {
            _webView = null;
            return true;
        }
        return false;
    }

    void OnReceivedMessage(UniWebView webView, UniWebViewMessage message) {
        /**
         * From WebView's message.
         * 
         * Ex:
         * uniwebview://command?foo=true&bar=false&num=1
         */
        Debug.Log(message.rawMessage);
        Debug.Log(message.path); // command
        Debug.Log(message.args["foo"]); // true  (string)
        Debug.Log(message.args["bar"]); // false (string)
        Debug.Log(message.args["num"]); // 1     (string)
    }

    void OnEvalJavaScriptFinished(UniWebView webView, string result) {
        Debug.Log("js result: " + result);
    //  tipTextMesh.text = "<color=#000000>" + result + "</color>";
    }

    UniWebViewEdgeInsets InsetsForScreenOreitation(UniWebView webView, UniWebViewOrientation orientation) {
        /*
        int bottomInset = (int)(UniWebViewHelper.screenHeight * 0.1f);

        if (orientation == UniWebViewOrientation.Portrait) {
            return new UniWebViewEdgeInsets(5,5,bottomInset,5);
        } else {
            return new UniWebViewEdgeInsets(5,5,bottomInset,5);
        }
        */
        return new UniWebViewEdgeInsets(0, 0, 0, 0);
    }

    // Update is called once per frame
    void Update () {

    }
}

file1.html

<a href="uniwebview://command?foo=bar">button</a>

file2.js

location.href = "uniwebview://command?foo=bar";