Bug 1361879: Ensure that sdnAccessible holds a strong reference to its creating AccessibleWrap if it was instantiated as a tearoff; r=tbsaunde

MozReview-Commit-ID: CCgwa7BHUBK

--HG--
extra : rebase_source : 974cadff7b42e3b38ba547b85792b00ebb12aecf
extra : histedit_source : 56a8ed517994bafc02594ba2d9fbf014b47b89da%2C9c63efae8b6a3e056b76c788b6a3f21ddbd27972

accessible/windows/msaa/AccessibleWrap.cpp

@@ -134,7 +134,7 @@ AccessibleWrap::QueryInterface(REFIID iid, void** ppv)
     if (IsDefunct() || (!HasOwnContent() && !IsDoc()))
       return E_NOINTERFACE;
 
-    *ppv = static_cast<ISimpleDOMNode*>(new sdnAccessible(GetNode()));
+    *ppv = static_cast<ISimpleDOMNode*>(new sdnAccessible(WrapNotNull(this)));
   }
 
   if (nullptr == *ppv) {

accessible/windows/sdn/sdnAccessible-inl.h

@@ -21,11 +21,23 @@ sdnAccessible::GetDocument() const
   return GetExistingDocAccessible(mNode->OwnerDoc());
 }
 
-inline Accessible*
-sdnAccessible::GetAccessible() const
+inline AccessibleWrap*
+sdnAccessible::GetAccessible()
 {
+  if (mWrap) {
+    return mWrap;
+  }
+
   DocAccessible* document = GetDocument();
-  return document ? document->GetAccessibleEvenIfNotInMap(mNode) : nullptr;
+  if (!document) {
+    return nullptr;
+  }
+
+  // Once we have an accessible, we should hold a reference to it so that we
+  // may preserve object identity.
+  mWrap =
+    static_cast<AccessibleWrap*>(document->GetAccessibleEvenIfNotInMap(mNode));
+  return mWrap;
 }
 
 } // namespace a11y

accessible/windows/sdn/sdnAccessible.cpp

@@ -38,7 +38,7 @@ sdnAccessible::QueryInterface(REFIID aREFIID, void** aInstancePtr)
     return S_OK;
   }
 
-  AccessibleWrap* accessible = static_cast<AccessibleWrap*>(GetAccessible());
+  AccessibleWrap* accessible = GetAccessible();
   if (accessible)
     return accessible->QueryInterface(aREFIID, aInstancePtr);
 
@@ -98,7 +98,7 @@ sdnAccessible::get_nodeInfo(BSTR __RPC_FAR* aNodeName,
   // application can compare this to the childID we return for events such as
   // focus events, to correlate back to data nodes in their internal object
   // model.
-  Accessible* accessible = GetAccessible();
+  AccessibleWrap* accessible = GetAccessible();
   if (accessible) {
     *aUniqueID = AccessibleWrap::GetChildIDFor(accessible);
   } else {

accessible/windows/sdn/sdnAccessible.h

@@ -12,6 +12,7 @@
 #include "IUnknownImpl.h"
 
 #include "mozilla/Attributes.h"
+#include "mozilla/NotNull.h"
 
 namespace mozilla {
 namespace a11y {
@@ -27,6 +28,12 @@ public:
   }
   ~sdnAccessible() { }
 
+  explicit sdnAccessible(NotNull<AccessibleWrap*> aAccWrap)
+    : mNode(aAccWrap->GetNode())
+    , mWrap(aAccWrap)
+  {
+  }
+
   /**
    * Retrun if the object is defunct.
    */
@@ -40,7 +47,7 @@ public:
   /*
    * Return associated accessible if any.
    */
-  Accessible* GetAccessible() const;
+  AccessibleWrap* GetAccessible();
 
   //IUnknown
   DECL_IUNKNOWN
@@ -111,6 +118,7 @@ public:
 
 private:
   nsCOMPtr<nsINode> mNode;
+  RefPtr<AccessibleWrap> mWrap;
 };
 
 } // namespace a11y