App stops working as soon it starts.

Hi, I wrote my own plugin for Google Admob and Analytics, but as soon as the app starts, it closes.

This is the plugin code:

 package com.demilp.plugins;
 
 import android.os.Bundle;
 import android.view.Gravity;
 import android.widget.FrameLayout.LayoutParams;
 import android.widget.LinearLayout;
 
 import com.google.android.gms.ads.*;
 import com.google.android.gms.analytics.GoogleAnalytics;
 import com.google.android.gms.analytics.HitBuilders;
 import com.google.android.gms.analytics.Tracker;
 import com.unity3d.player.UnityPlayerNativeActivity;
 
 public class Plugins extends UnityPlayerNativeActivity  {
 
     //Variables de Analytics
     private Tracker tracker;
     
     //Variables de AdMob
     private AdView adView;
     private InterstitialAd interstitial;
     //Mi Nexus 5 ID 04911cc734379b2b
     
     
     //Metodos Compartidos
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
     }
     
     @Override
     protected void onStart() {
         super.onStart();
         GoogleAnalytics.getInstance(this).reportActivityStart(this);
     }
 
     @Override
     protected void onResume() {
         super.onResume();
         if (adView != null) {
             adView.resume();
         }
     }
 
       @Override
       protected void onPause() {
         if (adView != null) {
           adView.pause();
         }
         super.onPause();
       }
     
     
     @Override
     protected void onStop() {
         super.onStop();
         GoogleAnalytics.getInstance(this).reportActivityStop(this);
     }
     
     @Override
     protected void onDestroy() {
         DestroyAdBanner();
         super.onDestroy();
     }
     
     
     //Metodos de Analytics
     public void InitAnalytics(String propertyID)
     {
         if(tracker == null)
         {
             GoogleAnalytics analytics = GoogleAnalytics.getInstance(this);
             tracker = analytics.newTracker(propertyID);
         }
         
     }
     
     
     public void SendScreen(String screenName)
     {
         tracker.setScreenName(screenName);
         tracker.send(new HitBuilders.AppViewBuilder().build());
     }
     
     public void SendEvent(String category, String action, String label, long value)
     {
         tracker.send(new HitBuilders.EventBuilder()
         .setCategory(category)
         .setAction(action)
         .setLabel(label)
         .setValue(value)
         .build());
     }
     public void SendEvent(String category, String action, String label)
     {
         tracker.send(new HitBuilders.EventBuilder()
         .setCategory(category)
         .setAction(action)
         .setLabel(label)
         .build());
     }
     public void SendEvent(String category, String action)
     {
         tracker.send(new HitBuilders.EventBuilder()
         .setCategory(category)
         .setAction(action)
         .build());
     }
     
     public void SendTiming(String category, long value, String name, String label)
     {
         tracker.send(new HitBuilders.TimingBuilder()
         .setCategory(category)
         .setValue(value)
         .setVariable(name)
         .setLabel(label)
         .build());
     }
     public void SendTiming(String category, long value, String name)
     {
         tracker.send(new HitBuilders.TimingBuilder()
         .setCategory(category)
         .setValue(value)
         .setVariable(name)
         .build());
     }
     public void SendTiming(String category, long value)
     {
         tracker.send(new HitBuilders.TimingBuilder()
         .setCategory(category)
         .setValue(value)
         .build());
     }
 
     
     //Metodos de AdMob    
     public void CreateAdBanner(String adUnitID, int adSize, String testDeviceID, boolean isTesting){
         // Create an ad.
         
         //adView.setX([float x]);
         //adView.sety([float y]);
 
         adView = new AdView(this);
         
         switch (adSize){
             case 0:
                 adView.setAdSize(AdSize.BANNER);
                 break;
             case 1:
                 adView.setAdSize(AdSize.FULL_BANNER);
                 break;
             case 2:
                 adView.setAdSize(AdSize.LEADERBOARD);
                 break;
             case 3:
                 adView.setAdSize(AdSize.MEDIUM_RECTANGLE);
                 break;
             case 4:
                 adView.setAdSize(AdSize.SMART_BANNER);
                 break;
             case 5:
                 adView.setAdSize(AdSize.WIDE_SKYSCRAPER);
                 break;
             default:
                 adView.setAdSize(AdSize.SMART_BANNER);
                 break;
         }
         
         
         adView.setAdUnitId(adUnitID);
 
 
         
         // Create an ad request. Check logcat output for the hashed device ID to
         // get test ads on a physical device.
         AdRequest adRequest;
         if(isTesting){
             adRequest = new AdRequest.Builder()
                 .addTestDevice(AdRequest.DEVICE_ID_EMULATOR)
                 .addTestDevice(testDeviceID)
                 .build();
         }else{
             adRequest = new AdRequest.Builder().build();
         }
         // Start loading the ad in the background.
         adView.loadAd(adRequest);
     }
     
     
     
     
     public void ShowAdBanner(int gravity){
         
         if(adView != null){
             LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
             
             
             LinearLayout layout = (LinearLayout) findViewById(R.id.linearLayout);
             
             switch(gravity){
             case 0:
                 layout.setGravity(Gravity.NO_GRAVITY);
                 break;
             case 1:
                 layout.setGravity(Gravity.CENTER_HORIZONTAL);
                 break;
             case 2:
                 layout.setGravity(Gravity.LEFT);
                 break;
             case 3:
                 layout.setGravity(Gravity.RIGHT);
                 break;
             case 4:
                 layout.setGravity(Gravity.FILL_HORIZONTAL);
                 break;
             case 5:
                 layout.setGravity(Gravity.CENTER_VERTICAL);
                 break;
             case 6:
                 layout.setGravity(Gravity.CENTER);
                 break;
             case 7:
                 layout.setGravity(Gravity.TOP);
                 break;
             case 8:
                 layout.setGravity(Gravity.BOTTOM);
                 break;
             case 9:
                 layout.setGravity(Gravity.FILL_VERTICAL);
                 break;
             }
             
             
             if(layout.indexOfChild(adView) >= 0){
                 adView.setLayoutParams(params);
                 layout.addView(adView);
             }
         }
     }
     
     
     
     
     public void HideAdBanner(){
         if(adView != null){
             LinearLayout layout = (LinearLayout) findViewById(R.id.linearLayout);
             layout.removeView(adView);
         }
     }
     
     public void DestroyAdBanner(){
         if (adView != null) {
             HideAdBanner();
             adView.destroy();
         }
     }
     
     public void CreateAdInterstitial(String adUnitID, String testDeviceID){
         interstitial = new InterstitialAd(this);
         interstitial.setAdUnitId(adUnitID);
 
         // Create ad request.
         AdRequest.Builder adRequestBuilder = new AdRequest.Builder().addTestDevice(AdRequest.DEVICE_ID_EMULATOR).addTestDevice("testDeviceID");
 
         //Add listener
         interstitial.setAdListener(new AdListener() {
             @Override
             public void onAdLoaded() {
                 ShowAdInterstitial();
             }
 
 
         });
         
         
         // Begin loading your interstitial.
         interstitial.loadAd(adRequestBuilder.build());
     }
     
     private void ShowAdInterstitial() {
         if (interstitial.isLoaded()) {
             
             interstitial.show();
             
         }
     }
     
 }
 

I replace the activity in the manifest with com.demilp.plugins.Plugins and copy google-play-services.jar to Assets/Plugins/Android. Am i missing something?