Send origin referrer for YouTube embeds

Unfortunately, YouTube blocks embedded views in iframes that don't send
a referrer. To fix them as-is, we explicitly provide the origin.

A future implementation might offer a config option to either offer a
YouTube video as iframe, requiring to send referrers towards Google, or
provide just a link (with thumbnail), which requires no referrer, iframe
or JavaScript.

https://support.google.com/youtube/answer/171780#zippy=%2Cprovide-an-http-referrer-header-to-enable-video-playback
https://developers.google.com/youtube/terms/required-minimum-functionality#embedded-player-api-client-identity

Author: Mynacol

bridges/AnisearchBridge.php

@@ -72,7 +72,7 @@ public function collectData()
                     $ytlink = <<<EOT
                         <br /><iframe width="560" height="315" src="$trailer" title="YouTube video player"
                         frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
-                        referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+                        referrerpolicy="strict-origin" allowfullscreen></iframe>
                     EOT;
                 }
             }

bridges/AssociatedPressNewsBridge.php

@@ -215,7 +215,7 @@ private function processMediaPlaceholders($html, $id)
 
                 if ($media['type'] === 'YouTube') {
                     $div->outertext = <<<EOD
-	<iframe src="https://www.youtube.com/embed/{$media['externalId']}" width="560" height="315">
+	<iframe src="https://www.youtube.com/embed/{$media['externalId']}" width="560" height="315" referrerpolicy="strict-origin">
 	</iframe>
 EOD;
                 }
@@ -251,7 +251,7 @@ private function processVideo($storyContent)
         if ($video['type'] === 'YouTube') {
             $url = 'https://www.youtube.com/embed/' . $video['externalId'];
             $html = <<<EOD
-<iframe width="560" height="315" src="{$url}" frameborder="0" allowfullscreen></iframe>
+<iframe width="560" height="315" src="{$url}" frameborder="0" allowfullscreen referrerpolicy="strict-origin"></iframe>
 EOD;
         } else {
             $html = <<<EOD

bridges/GizmodoBridge.php

@@ -76,6 +76,7 @@ private function handleIframeTags($html)
     {
         foreach ($html->find('iframe') as $iframe) {
             $iframe->src = urljoin($this->getURI(), $iframe->src);
+            $iframe->referrerpolicy = 'strict-origin';
         }
     }
 }

bridges/GolemBridge.php

@@ -124,7 +124,7 @@ private function extractContent($page, $prevcontent)
                     $placeholders[$i]->innertext .= <<<EOT
                         <iframe width="560" height="315" src="$link" title="YouTube video player" frameborder="0"
                         allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
-                        referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>';
+                        referrerpolicy="strict-origin" allowfullscreen></iframe>';
                     EOT;
                     break;
                 }

bridges/HeiseBridge.php

@@ -213,7 +213,7 @@ private function addArticleToItem($item, $article)
                 $ytiframe = <<<EOT
                     <iframe width="560" height="315" src="https://$link[0] title="YouTube video player" frameborder="0"
                     allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
-                    referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
+                    referrerpolicy="strict-origin" allowfullscreen></iframe>
                 EOT;
                 //check if video is in header or article for correct possitioning
                 if (strpos($header->innertext, $link[0])) {

bridges/ReutersBridge.php

@@ -543,6 +543,7 @@ private function handleArticleContent($contents)
 	src="{$url}"
 	frameborder="0" 
 	allowfullscreen
+	referrerpolicy="strict-origin"
 >
 </iframe>
 EOD;

bridges/YouTubeCommunityTabBridge.php

@@ -240,7 +240,7 @@ private function getAttachments($details)
 
                 $content = <<<EOD
 <iframe width="100%" height="410" src="https://www.youtube.com/embed/{$attachments->videoRenderer->videoId}" 
-frameborder="0" allow="encrypted-media;" allowfullscreen></iframe>
+frameborder="0" allow="encrypted-media;" allowfullscreen referrerpolicy="strict-origin"></iframe>
 EOD;
             } elseif (isset($attachments->backstageImageRenderer)) {
                 // Image

bridges/YouTubeFeedExpanderBridge.php

@@ -76,7 +76,7 @@ protected function parseItem(array $item)
         }
         $embed = $embedURI . 'embed/' . $id;
         if ($this->getInput('embed')) {
-            $iframe_fmt = '<iframe width="448" height="350" src="%s" title="%s" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>'; //phpcs:ignore
+            $iframe_fmt = '<iframe width="448" height="350" src="%s" title="%s" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin" allowfullscreen></iframe>'; //phpcs:ignore
             $iframe = sprintf($iframe_fmt, $embed, $item['title']) . '<br>';
             $item['content'] = $iframe . $item['content'];
         }