This gist is used to implement Chrome Custom Tab in your Android app. For further details :

MainActivity.java

package com.droidmentor.chromecustomtab;

import android.app.PendingIntent;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.support.customtabs.CustomTabsIntent;
import android.support.v4.content.res.ResourcesCompat;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    String TAG = "MainActivity";

    Button btnLaunch;

    String url;
    public static MainActivity instance = null;

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

        instance = this;

        btnLaunch = (Button) findViewById(R.id.btnLaunch);
        btnLaunch.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                // Loading url
                url = "http://droidmentor.com/";

                // CustomTabsIntent.Builder used to configure CustomTabsIntent.
                CustomTabsIntent.Builder builder = new CustomTabsIntent.Builder().setShowTitle(true);

                // Change the background color of the Toolbar.
                builder.setToolbarColor(ResourcesCompat.getColor(getResources(), R.color.colorPrimary, null));

                // Configure custom enter and exit animations
                builder.setStartAnimations(MainActivity.this, R.anim.slide_in_right, R.anim.slide_out_left);
                builder.setExitAnimations(MainActivity.this, R.anim.slide_in_left, R.anim.slide_out_right);

                // Setting a custom back button
                builder.setCloseButtonIcon(BitmapFactory.decodeResource(
                        getResources(), R.drawable.ic_arrow_back));

                // Hide status bar once the user scrolls down the content
                builder.enableUrlBarHiding();

                // For adding menu item
                builder.addMenuItem("Share", getItem());

                // For adding Action button
                builder.setActionButton(BitmapFactory.decodeResource(getResources(),
                        R.drawable.ic_share), "Share", getItem(), true);

                // CustomTabsIntent used to launch the URL
                CustomTabsIntent customTabsIntent = builder.build();

                //Open the Custom Tab
                customTabsIntent.launchUrl(MainActivity.this, Uri.parse(url));


            }
        });


    }

    private PendingIntent getItem() {
        Intent shareIntent = new Intent(Intent.ACTION_SEND);
        shareIntent.setType("text/plain");
        shareIntent.putExtra(Intent.EXTRA_SUBJECT, "Droidmentor is a site, which contains android tutorials");
        Log.d(TAG, "setMenuItem: " + url);
        shareIntent.putExtra(Intent.EXTRA_TEXT, url);
        return PendingIntent.getActivity(this, 0, shareIntent, 0);
    }

}