Bug 1261599 - null check SendPBrowserConstructor return in ContentParent to avoid crashes on content process shutdown. r=smaug

MozReview-Commit-ID: 4LqDIeN9XRq

--HG--
extra : rebase_source : ff6edb2b80ac4e29374092d2637fc91886afec0d

dom/ipc/ContentParent.cpp

@@ -1201,10 +1201,12 @@ ContentParent::CreateBrowserOrApp(const TabContext& aContext,
         constructorSender->IsForApp(),
         constructorSender->IsForBrowser());
 
+      if (browser) {
         RefPtr<TabParent> constructedTabParent = TabParent::GetFrom(browser);
         constructedTabParent->SetOwnerElement(aFrameElement);
         return constructedTabParent;
       }
+    }
     return nullptr;
   }