Oilpan: Remove guardRef and guardDeref from TreeScope.

Source/core/html/HTMLMediaElement.cpp

Index: Source/core/html/HTMLMediaElement.cpp
diff --git a/Source/core/html/HTMLMediaElement.cpp b/Source/core/html/HTMLMediaElement.cpp
index 8904ce96bc1c6f41ebd7605b24ee1295a1d70ffa..5cb6af17424197e9f7c8acd78a24473ac0685572 100644
--- a/Source/core/html/HTMLMediaElement.cpp
+++ b/Source/core/html/HTMLMediaElement.cpp
@@ -327,6 +327,10 @@ HTMLMediaElement::~HTMLMediaElement()
     // See http://crbug.com/233654 for more details.
     m_completelyLoaded = true;
 
+    // With Oilpan load events on the Document are always delayed during
+    // sweeping so we don't need to explicitly increment and decrement
+    // load event delay counts.

[haraken, 2014/04/24 04:18:43]

I don't quite understand this. Do you need to comment out increment/decrement in
the destructor but not need to comment out other increments/decrements in this
file?

[Mads Ager (chromium), 2014/04/24 10:57:36]

Yes, have a look at the bug report that is referenced in the comment below.
These increments/decrements are only here to prevent a load event dispatch
during destruction. That is now handled in document explicitly so that *no*
destructors for objects in the oilpan heap can dispatch a document load event.

+#if !ENABLE(OILPAN)
     // Destroying the player may cause a resource load to be canceled,
     // which could result in Document::dispatchWindowLoadEvent() being
     // called via ResourceFetch::didLoadResource() then
@@ -334,10 +338,13 @@ HTMLMediaElement::~HTMLMediaElement()
     // object destruction, we use Document::incrementLoadEventDelayCount().
     // See http://crbug.com/275223 for more details.
     document().incrementLoadEventDelayCount();
+#endif
 
     clearMediaPlayerAndAudioSourceProviderClient();
 
+#if !ENABLE(OILPAN)
     document().decrementLoadEventDelayCount();
+#endif
 }
 
 void HTMLMediaElement::didMoveToNewDocument(Document& oldDocument)