Issue 3200 - Delay initialization for prerendered documents

composer.postload.js

Index: composer.postload.js
===================================================================
--- a/composer.postload.js
+++ b/composer.postload.js
@@ -577,10 +577,26 @@
             }
           });
         }
         break;
     }
   });
 
   if (window == window.top)
-    ext.backgroundPage.sendMessage({type: "composer.ready"});
+  {
+    if (document.visibilityState == "prerender")

[Sebastian Noack, 2017/05/20 11:19:06]

Note that the visibility API doesn't exists before Safari 7. But that shouldn't
be a problem because this check (and the one in include.preload.js) will just
evaluate to false and the behavior will remain the same as before on Safari 6,
where there is no document.visibilityState, right? And since Safari 6 doesn't do
prerendering it shouldn't be effected by the bug we address here, anyway.

[Manish Jethani, 2017/05/20 19:01:06]

Yes, then visibilityState should just be undefined. If it's anything other than
"prerender" it'll just do what it's been doing so far.

The "prerender" value was added back in Safari 7 so I think this'll fix the
issue for all versions that have this issue.

https://developer.apple.com/library/content/releasenotes/General/WhatsNewInSa...

[Sebastian Noack, 2017/05/21 20:31:01]

Yeah, I supposed so. Thanks for confirming my assumption. However, it is not
great to duplicate this logic. Note that composer.postload.js runs after
include.preload.js in the same context. So how about moving the logic tat runs
code as soon as the document visible into a function?

[Manish Jethani, 2017/08/24 14:07:57]

Done.

+    {
+      let onVisibilitychange = function()
+      {
+        document.removeEventListener("visibilitychange", onVisibilitychange);
+

[Sebastian Noack, 2017/05/21 20:31:01]

Nit: The blank line here looks weird.

[Manish Jethani, 2017/08/24 14:07:57]

Acknowledged.

+        ext.backgroundPage.sendMessage({type: "composer.ready"});
+      };
+
+      document.addEventListener("visibilitychange", onVisibilitychange);
+    }
+    else
+    {
+      ext.backgroundPage.sendMessage({type: "composer.ready"});
+    }
+  }
 }