Don't hard-code center justify of AdSense ads. Let position be customized with CSS.

assets/javascripts/discourse/components/google-adsense.js.es6

@@ -115,7 +115,7 @@ export default Ember.Component.extend({
   },
 
   adWrapperStyle: function() {
-    return `width: ${this.get('ad_width')}px; height: ${this.get('ad_height')}px; margin:0 auto;`.htmlSafe();
+    return `width: ${this.get('ad_width')}px; height: ${this.get('ad_height')}px;`.htmlSafe();
   }.property('ad_width', 'ad_height'),
 
   adInsStyle: function() {
@@ -123,7 +123,7 @@ export default Ember.Component.extend({
   }.property('adWrapperStyle'),
 
   adWrapperStyleMobile: function() {
-    return `width: ${this.get('ad_mobile_width')}px; height: ${this.get('ad_mobile_height')}px; margin:0 auto;`.htmlSafe();
+    return `width: ${this.get('ad_mobile_width')}px; height: ${this.get('ad_mobile_height')}px;`.htmlSafe();
   }.property('ad_mobile_width', 'ad_mobile_height'),
 
   adTitleStyleMobile: function() {

assets/javascripts/discourse/templates/components/google-adsense.hbs

@@ -1,7 +1,7 @@
 {{#if checkTrustLevels}}
   {{#if site.mobileView}}
     <div class="google-adsense-label" style={{adTitleStyleMobile}}><h2>ADVERTISEMENT</h2></div>
-    <div style={{adWrapperStyleMobile}}>
+    <div class="google-adsense-content" style={{adWrapperStyleMobile}}>
       <ins class="adsbygoogle"
         style={{adInsStyleMobile}}
         data-ad-client="ca-pub-{{publisher_id}}"
@@ -14,7 +14,7 @@
     </div>
   {{else}}
     <div class="google-adsense-label"><h2>ADVERTISEMENT</h2></div>
-    <div style={{adWrapperStyle}}>
+    <div class="google-adsense-content" style={{adWrapperStyle}}>
       <ins class="adsbygoogle"
         style={{adInsStyle}}
         data-ad-client="ca-pub-{{publisher_id}}"

plugin.rb

@@ -63,6 +63,10 @@ register_css <<CSS
   font-weight: normal;
 }
 
+.google-adsense .google-adsense-content {
+  margin: 0 auto;
+}
+
 .google-dfp-ad .google-dfp-ad-label {
   width: 728px;
   margin: 0 auto;