1 files changed, 82 insertions, 0 deletions
diff --git a/layout/base/tests/browser_bug839103.js b/layout/base/tests/browser_bug839103.js
new file mode 100644
index 0000000000..fd20b82029
--- /dev/null
+++ b/layout/base/tests/browser_bug839103.js
@@ -0,0 +1,82 @@
+const gTestRoot = getRootDirectory(gTestPath).replace(
+  "chrome://mochitests/content/",
+  "http://127.0.0.1:8888/"
+);
+
+add_task(async function test() {
+  await BrowserTestUtils.withNewTab(
+    { gBrowser, url: gTestRoot + "file_bug839103.html" },
+    async function (browser) {
+      await SpecialPowers.spawn(browser, [gTestRoot], testBody);
+    }
+  );
+});
+
+// This function runs entirely in the content process. It doesn't have access
+// any free variables in this file.
+async function testBody(testRoot) {
+  const gStyleSheet = "bug839103.css";
+
+  function unexpectedContentEvent(event) {
+    ok(false, "Received a " + event.type + " event on content");
+  }
+
+  // We've seen the original stylesheet in the document.
+  // Now add a stylesheet on the fly and make sure we see it.
+  let doc = content.document;
+  doc.styleSheetChangeEventsEnabled = true;
+  doc.addEventListener(
+    "StyleSheetApplicableStateChanged",
+    unexpectedContentEvent
+  );
+  doc.defaultView.addEventListener(
+    "StyleSheetApplicableStateChanged",
+    unexpectedContentEvent
+  );
+
+  let link = doc.createElement("link");
+  link.setAttribute("rel", "stylesheet");
+  link.setAttribute("type", "text/css");
+  link.setAttribute("href", testRoot + gStyleSheet);
+
+  let stateChanged = ContentTaskUtils.waitForEvent(
+    docShell.chromeEventHandler,
+    "StyleSheetApplicableStateChanged",
+    true
+  );
+  doc.body.appendChild(link);
+
+  info("waiting for applicable state change event");
+  let evt = await stateChanged;
+  info("received dynamic style sheet applicable state change event");
+  is(
+    evt.type,
+    "StyleSheetApplicableStateChanged",
+    "evt.type has expected value"
+  );
+  is(evt.target, doc, "event targets correct document");
+  is(evt.stylesheet, link.sheet, "evt.stylesheet has the right value");
+  is(evt.applicable, true, "evt.applicable has the right value");
+
+  stateChanged = ContentTaskUtils.waitForEvent(
+    docShell.chromeEventHandler,
+    "StyleSheetApplicableStateChanged",
+    true
+  );
+  link.sheet.disabled = true;
+
+  evt = await stateChanged;
+  is(
+    evt.type,
+    "StyleSheetApplicableStateChanged",
+    "evt.type has expected value"
+  );
+  info(
+    'received dynamic style sheet applicable state change event after media="" changed'
+  );
+  is(evt.target, doc, "event targets correct document");
+  is(evt.stylesheet, link.sheet, "evt.stylesheet has the right value");
+  is(evt.applicable, false, "evt.applicable has the right value");
+
+  doc.body.removeChild(link);
+}