Oilpan: Prepare to move AXObjectCache to the heap

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index a03e9fdd052455f771809d9533c3753b33d36df7..8578ba3f6dcc803dbb80ba4c8e85d4babb34286c 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -2207,9 +2207,11 @@ Document& Document::axObjectCacheOwner() const
 void Document::clearAXObjectCache()

[haraken, 2015/04/28 10:45:21]

It is unsafe to land this CL at the moment since Document's destructor is
calling clearAXObjectCache().

We need to wait for https://codereview.chromium.org/1089813004/ to land and
remove clearAXObjectCache() from the destructor. However, it's not easy to
remove it since currently Document::detach is not always called for all
Documents.

 {
     ASSERT(&axObjectCacheOwner() == this);
-    // Clear the cache member variable before calling delete because attempts
-    // are made to access it during destruction.
-    m_axObjectCache.clear();
+    // Clear the cache member variable before calling discard because attempts

[haraken, 2015/04/28 10:45:21]

What is discard?

[keishi, 2015/05/28 06:49:15]

My mistake. I got confused. Reverted.

+    // are made to access it during discard.
+    OwnPtrWillBeRawPtr<AXObjectCache> cache = m_axObjectCache.release();
+    if (cache)
+        cache->dispose();

[haraken, 2015/04/28 10:45:21]

Nit:

if (m_axObjectCache)
  m_axObjectCache->dispose();
m_axObjectCache.clear();

[keishi, 2015/05/28 06:49:15]

Done.

 }
 
 AXObjectCache* Document::existingAXObjectCache() const
@@ -5705,6 +5707,7 @@ DEFINE_TRACE(Document)
     visitor->trace(m_activeHoverElement);
     visitor->trace(m_documentElement);
     visitor->trace(m_titleElement);
+    visitor->trace(m_axObjectCache);
     visitor->trace(m_markers);
     visitor->trace(m_cssTarget);
     visitor->trace(m_currentScriptStack);