Bug 1579437 - Check for discarded BrowsingContext in more places, r=farre

Differential Revision: https://phabricator.services.mozilla.com/D45088

--HG--
extra : moz-landing-system : lando

docshell/base/BrowsingContext.cpp

@@ -945,7 +945,12 @@ void BrowsingContext::PostMessageMoz(JSContext* aCx,
                  aSubjectPrincipal, aError);
 }
 
-void BrowsingContext::Transaction::Commit(BrowsingContext* aBrowsingContext) {
+nsresult BrowsingContext::Transaction::Commit(
+    BrowsingContext* aBrowsingContext) {
+  if (NS_WARN_IF(aBrowsingContext->IsDiscarded())) {
+    return NS_ERROR_FAILURE;
+  }
+
   if (!Validate(aBrowsingContext, nullptr)) {
     MOZ_CRASH("Cannot commit invalid BrowsingContext transaction");
   }
@@ -973,7 +978,9 @@ void BrowsingContext::Transaction::Commit(BrowsingContext* aBrowsingContext) {
   }
 
   Apply(aBrowsingContext);
+  return NS_OK;
 }
+
 bool BrowsingContext::Transaction::Validate(BrowsingContext* aBrowsingContext,
                                             ContentParent* aSource) {
 #define MOZ_BC_FIELD(name, ...)                                        \

docshell/base/BrowsingContext.h

@@ -357,8 +357,10 @@ class BrowsingContext : public nsWrapperCache, public BrowsingContextBase {
     // in all processes. This method will call the correct `MaySet` and
     // `DidSet` methods, as well as move the value.
     //
+    // If the target has been discarded, changes will be ignored.
+    //
     // NOTE: This method mutates `this`, resetting all members to `Nothing()`
-    void Commit(BrowsingContext* aOwner);
+    nsresult Commit(BrowsingContext* aOwner);
 
     // This method should be called before invoking `Apply` on this transaction
     // object.

dom/media/mediacontrol/MediaControlUtils.h

@@ -63,7 +63,7 @@ const char* ToMediaControlActionsStr(
 
 void NotifyMediaStarted(uint64_t aWindowID) {
   RefPtr<BrowsingContext> bc = GetBrowingContextByWindowID(aWindowID);
-  if (!bc) {
+  if (!bc || bc->IsDiscarded()) {
     return;
   }
   LOG("Notify media started in BC %" PRId64, bc->Id());
@@ -73,7 +73,7 @@ void NotifyMediaStarted(uint64_t aWindowID) {
 
 void NotifyMediaStopped(uint64_t aWindowID) {
   RefPtr<BrowsingContext> bc = GetBrowingContextByWindowID(aWindowID);
-  if (!bc) {
+  if (!bc || bc->IsDiscarded()) {
     return;
   }
   LOG("Notify media stopped in BC %" PRId64, bc->Id());
@@ -83,7 +83,7 @@ void NotifyMediaStopped(uint64_t aWindowID) {
 
 void NotifyMediaAudibleChanged(uint64_t aWindowID, bool aAudible) {
   RefPtr<BrowsingContext> bc = GetBrowingContextByWindowID(aWindowID);
-  if (!bc) {
+  if (!bc || bc->IsDiscarded()) {
     return;
   }
   LOG("Notify media became %s in BC %" PRId64,