Implement DOM page onvisibilitychange.

dom/base/nsGkAtomList.h

@@ -950,6 +950,7 @@ GK_ATOM(onupdateready, "onupdateready")
 GK_ATOM(onupgradeneeded, "onupgradeneeded")
 GK_ATOM(onussdreceived, "onussdreceived")
 GK_ATOM(onversionchange, "onversionchange")
+GK_ATOM(onvisibilitychange, "onvisibilitychange")
 GK_ATOM(onvoicechange, "onvoicechange")
 GK_ATOM(onvoiceschanged, "onvoiceschanged")
 GK_ATOM(onvrdisplayconnect, "onvrdisplayconnect")

dom/events/EventNameList.h

@@ -674,6 +674,10 @@ DOCUMENT_ONLY_EVENT(selectionchange,
                     eSelectionChange,
                     EventNameType_HTMLXUL,
                     eBasicEventClass)
+DOCUMENT_ONLY_EVENT(visibilitychange,
+                    eVisibilityChange,
+                    EventNameType_HTMLXUL,
+                    eBasicEventClass)
 
 NON_IDL_EVENT(MozMouseHittest,
               eMouseHitTest,

dom/webidl/Document.webidl

@@ -275,10 +275,11 @@ partial interface Document {
     object registerElement(DOMString name, optional ElementRegistrationOptions options);
 };
 
-// http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/PageVisibility/Overview.html#sec-document-interface
+// https://w3c.github.io/page-visibility/#extensions-to-the-document-interface
 partial interface Document {
   readonly attribute boolean hidden;
   readonly attribute VisibilityState visibilityState;
+           attribute EventHandler onvisibilitychange;
 };
 
 // http://dev.w3.org/csswg/cssom/#extensions-to-the-document-interface

testing/web-platform/tests/page-visibility/idlharness.html

@@ -4,7 +4,7 @@
 <meta charset="utf-8">
 <title>Page Visibility IDL tests</title>
 <link rel="author" title="W3C" href="http://www.w3.org/" />
-<link rel="help" href="http://www.w3.org/TR/page-visibility/#sec-document-interface"/>
+<link rel="help" href="https://w3c.github.io/page-visibility/"/>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <script src="/resources/WebIDLParser.js"></script>
@@ -16,6 +16,10 @@
 <pre id='untested_idl' style='display:none'>
 interface Document {
 };
+
+[TreatNonObjectAsNull]
+callback EventHandlerNonNull = any (Event event);
+typedef EventHandlerNonNull? EventHandler;
 </pre>
 
 <pre id='idl'>

widget/EventMessageList.h

@@ -448,6 +448,9 @@ NS_EVENT_MESSAGE(eEditorInput)
 NS_EVENT_MESSAGE(eSelectStart)
 NS_EVENT_MESSAGE(eSelectionChange)
 
+// visibility change
+NS_EVENT_MESSAGE(eVisibilityChange)
+
 // Details element events.
 NS_EVENT_MESSAGE(eToggle)