Bug 1457048 - Ensure origins with autoplay-media exact permission can autoplay. r=bryce,johannh

Sites which are whitelisted should be allowed to autoplay audible media.
So check whether a HTMLMediaElement's owner doc's principal has an exact
"autoplay-media" permission. This ensures whitelisted origins can autoplay,
but sub-origins of whitelisted origins need their own permission.

MozReview-Commit-ID: 2IO5KIyplEa

--HG--
extra : rebase_source : 4d9afdec0caa4a82b53bedfd645f259a5c760e4d

browser/modules/SitePermissions.jsm

@@ -600,6 +600,16 @@ var gPermissionObject = {
    *    don't want to expose a "Hide Prompt" button to the user through pageinfo.
    */
 
+  "autoplay-media": {
+    exactHostMatch: true,
+    getDefault() {
+      if (Services.prefs.getBoolPref("media.autoplay.enabled")) {
+        return SitePermissions.ALLOW;
+      }
+      return SitePermissions.BLOCK;
+    }
+  },
+
   "image": {
     states: [ SitePermissions.ALLOW, SitePermissions.BLOCK ],
   },

dom/media/AutoplayPolicy.cpp

@@ -10,18 +10,13 @@
 #include "mozilla/Preferences.h"
 #include "mozilla/dom/HTMLMediaElement.h"
 #include "mozilla/dom/HTMLMediaElementBinding.h"
+#include "nsContentUtils.h"
 #include "nsIDocument.h"
 #include "MediaManager.h"
 
 namespace mozilla {
 namespace dom {
 
-/* static */ bool
-AutoplayPolicy::IsDocumentAllowedToPlay(nsIDocument* aDoc)
-{
-  return aDoc ? aDoc->HasBeenUserActivated() : false;
-}
-
 /* static */ bool
 AutoplayPolicy::IsMediaElementAllowedToPlay(NotNull<HTMLMediaElement*> aElement)
 {
@@ -45,7 +40,7 @@ AutoplayPolicy::IsMediaElementAllowedToPlay(NotNull<HTMLMediaElement*> aElement)
     // If elelement is blessed, it would always be allowed to play().
     return aElement->IsBlessed() ||
            EventStateManager::IsHandlingUserInput();
-   }
+  }
 
   // Muted content
   if (aElement->Volume() == 0.0 || aElement->Muted()) {
@@ -59,7 +54,18 @@ AutoplayPolicy::IsMediaElementAllowedToPlay(NotNull<HTMLMediaElement*> aElement)
     return true;
   }
 
-  return AutoplayPolicy::IsDocumentAllowedToPlay(aElement->OwnerDoc());
+  // Whitelisted.
+  if (nsContentUtils::IsExactSitePermAllow(
+        aElement->NodePrincipal(), "autoplay-media")) {
+    return true;
+  }
+
+  // Activated by user gesture.
+  if (aElement->OwnerDoc()->HasBeenUserActivated()) {
+    return true;
+  }
+
+  return false;
 }
 
 } // namespace dom

dom/media/AutoplayPolicy.h

@@ -25,14 +25,13 @@ class HTMLMediaElement;
  * conditions is true.
  * 1) Owner document is activated by user gestures
  *    We restrict user gestures to "mouse click", "keyboard press" and "touch".
- * 2) Muted media content or video without audio content
+ * 2) Muted media content or video without audio content.
+ * 3) Document's origin has the "autoplay-media" permission.
  */
 class AutoplayPolicy
 {
 public:
   static bool IsMediaElementAllowedToPlay(NotNull<HTMLMediaElement*> aElement);
-private:
-  static bool IsDocumentAllowedToPlay(nsIDocument* aDoc);
 };
 
 } // namespace dom