Backed out changeset ccb5b3503b66 (bug 1362212)

browser/base/content/browser.js

@@ -1547,6 +1547,20 @@ var gBrowserInit = {
       this.gmpInstallManager.simpleCheckAndInstall().then(null, () => {});
     }, {timeout: 1000 * 60});
 
+    // Report via telemetry whether we're able to play MP4/H.264/AAC video.
+    // We suspect that some Windows users have a broken or have not installed
+    // Windows Media Foundation, and we'd like to know how many. We'd also like
+    // to know how good our coverage is on other platforms.
+    // Note: we delay by 90 seconds reporting this, as calling canPlayType()
+    // on Windows will cause DLLs to load, i.e. cause disk I/O.
+    setTimeout(() => {
+      let v = document.createElementNS("http://www.w3.org/1999/xhtml", "video");
+      let aacWorks = v.canPlayType("audio/mp4") != "";
+      Services.telemetry.getHistogramById("VIDEO_CAN_CREATE_AAC_DECODER").add(aacWorks);
+      let h264Works = v.canPlayType("video/mp4") != "";
+      Services.telemetry.getHistogramById("VIDEO_CAN_CREATE_H264_DECODER").add(h264Works);
+    }, 90 * 1000);
+
     SessionStore.promiseInitialized.then(() => {
       // Bail out if the window has been closed in the meantime.
       if (window.closed) {