Bug 1836128 - Implement source media for media elements and reference/update relevant platform tests r=padenot

Differential Revision: https://phabricator.services.mozilla.com/D189416

dom/html/HTMLMediaElement.cpp

@@ -2836,9 +2836,24 @@ void HTMLMediaElement::LoadFromSourceChildren() {
         return;
       }
     }
+    nsAutoString media;
+    child->GetAttr(nsGkAtoms::media, media);
+    HTMLSourceElement* childSrc = HTMLSourceElement::FromNode(child);
+    MOZ_ASSERT(childSrc, "Expect child to be HTMLSourceElement");
+    if (childSrc && !childSrc->MatchesCurrentMedia()) {
+      AutoTArray<nsString, 2> params = {media, src};
+      ReportLoadError("MediaLoadSourceMediaNotMatched", params);
+      DealWithFailedElement(child);
+      LOG(LogLevel::Debug,
+          ("%p Media did not match from <source>=%s type=%s media=%s", this,
+           NS_ConvertUTF16toUTF8(src).get(), NS_ConvertUTF16toUTF8(type).get(),
+           NS_ConvertUTF16toUTF8(media).get()));
+      return;
+    }
     LOG(LogLevel::Debug,
-        ("%p Trying load from <source>=%s type=%s", this,
-         NS_ConvertUTF16toUTF8(src).get(), NS_ConvertUTF16toUTF8(type).get()));
+        ("%p Trying load from <source>=%s type=%s media=%s", this,
+         NS_ConvertUTF16toUTF8(src).get(), NS_ConvertUTF16toUTF8(type).get(),
+         NS_ConvertUTF16toUTF8(media).get()));
 
     nsCOMPtr<nsIURI> uri;
     NewURIFromString(src, getter_AddRefs(uri));

testing/web-platform/meta/html/semantics/embedded-content/media-elements/loading-the-media-resource/resource-selection-source-media-env-change.html.ini

@@ -1,3 +0,0 @@
-[resource-selection-source-media-env-change.html]
-  [the <source> media attribute: no reaction to environment change]
-    expected: FAIL

testing/web-platform/tests/html/semantics/embedded-content/media-elements/loading-the-media-resource/resources/media-min-width.html

@@ -13,6 +13,7 @@ const rAF = () => new Promise(resolve => requestAnimationFrame(resolve));
 const hash = str => str.substr(str.lastIndexOf('#'));
 (async () => {
   const v = document.querySelector('video');
+  v.getBoundingClientRect(); // force layout flush. ensure viewport dimensions are up-to-date
   v.append(createSource('delayed-broken-video.py#a', '(min-width: 200px)'));
   v.append(createSource('delayed-broken-video.py#b'));
   await rAF();