Fire visibilitychange event on unload (behind the flag)

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 85872f18179bc4ea129f9572fcc591b5c599cc6b..d3ceae4d7ea6b75f5f5a8a4cd76a9aae4d61257d 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -1367,6 +1367,11 @@ PageVisibilityState Document::pageVisibilityState() const
     // http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/PageVisibility/Overview.html#dom-document-hidden
     if (!m_frame || !m_frame->page())
         return PageVisibilityStateHidden;
+    // While visibilitychange is being dispatched during unloading it is
+    // expected that the visibility is hidden regardless of the page's
+    // visibility.
+    if (m_loadEventProgress == UnloadVisibilityChangeInProgress)
+        return PageVisibilityStateHidden;
     return m_frame->page()->visibilityState();
 }
 
@@ -2763,6 +2768,17 @@ void Document::dispatchUnloadEvents()
             if (!m_frame)
                 return;
 
+            PageVisibilityState visibilityState = pageVisibilityState();
+            m_loadEventProgress = UnloadVisibilityChangeInProgress;
+            if (visibilityState != PageVisibilityStateHidden && RuntimeEnabledFeatures::visibilityChangeOnUnloadEnabled()) {
+                // Dispatch visibilitychange event, but don't bother doing
+                // other notifications as we're about to be unloaded.
+                dispatchEvent(Event::createBubble(EventTypeNames::visibilitychange));
+                dispatchEvent(Event::createBubble(EventTypeNames::webkitvisibilitychange));
+            }
+            if (!m_frame)
+                return;
+
             // The DocumentLoader (and thus its DocumentLoadTiming) might get destroyed
             // while dispatching the event, so protect it to prevent writing the end
             // time into freed memory.
@@ -2798,6 +2814,8 @@ Document::PageDismissalType Document::pageDismissalEventBeingDispatched() const
         return BeforeUnloadDismissal;
     if (m_loadEventProgress == PageHideInProgress)
         return PageHideDismissal;
+    if (m_loadEventProgress == UnloadVisibilityChangeInProgress)
+        return UnloadVisibilityChangeDismissal;
     if (m_loadEventProgress == UnloadEventInProgress)
         return UnloadDismissal;
     return NoDismissal;