Bug 1694865 part 16: Transitional implementation of IUnknown in MsaaAccessible/MsaaDocAccessible which delegates to AccessibleWrap. r=morgan

This is necessary to enable COM objects which aggregate AccessibleWrap/DocAccessibleWrap to aggregate MsaaAccessible/MsaaDocAccessible instead.
Ultimately, the IUnknown implementation will be moved out of AccessibleWrap altogether and into MsaaAccessible, but we can't do that yet.
Even though MsaaDocAccessible indirectly inherits from MsaaAccessible, we have to override QueryInterface due to the naming conflict with nsISupports.

Differential Revision: https://phabricator.services.mozilla.com/D112948

accessible/windows/msaa/MsaaAccessible.cpp

@@ -618,6 +618,20 @@ ITypeInfo* MsaaAccessible::GetTI(LCID lcid) {
   return gTypeInfo;
 }
 
+// IUnknown methods
+// XXX This delegation to AccessibleWrap is a necessary hack until we can move
+// the IUnknown implementation out of AccessibleWrap.
+
+STDMETHODIMP MsaaAccessible::QueryInterface(REFIID iid, void** ppv) {
+  return static_cast<AccessibleWrap*>(this)->QueryInterface(iid, ppv);
+}
+ULONG STDMETHODCALLTYPE MsaaAccessible::AddRef() {
+  return static_cast<AccessibleWrap*>(this)->AddRef();
+}
+ULONG STDMETHODCALLTYPE MsaaAccessible::Release() {
+  return static_cast<AccessibleWrap*>(this)->Release();
+}
+
 // IAccessible methods
 
 STDMETHODIMP

accessible/windows/msaa/MsaaAccessible.h

@@ -66,6 +66,11 @@ class MsaaAccessible : public ia2Accessible,
 
   static IDispatch* NativeAccessible(LocalAccessible* aAccessible);
 
+  // IUnknown
+  STDMETHODIMP QueryInterface(REFIID, void**) override;
+  ULONG STDMETHODCALLTYPE AddRef() override;
+  ULONG STDMETHODCALLTYPE Release() override;
+
   // IAccessible
   virtual /* [id][propget] */ HRESULT STDMETHODCALLTYPE get_accParent(
       /* [retval][out] */ IDispatch __RPC_FAR* __RPC_FAR* ppdispParent)

accessible/windows/msaa/MsaaDocAccessible.h

@@ -24,6 +24,15 @@ class MsaaDocAccessible : public DocAccessible {
   MsaaDocAccessible(dom::Document* aDocument, PresShell* aPresShell)
       : DocAccessible(aDocument, aPresShell) {}
 
+  DocAccessible* DocAcc();
+
+  // IUnknown
+  // XXX This override of QueryInterface is a necessary hack until we get rid
+  // of the inheritance of DocAccessible.
+  STDMETHODIMP QueryInterface(REFIID iid, void** ppv) override {
+    return MsaaAccessible::QueryInterface(iid, ppv);
+  }
+
   // IAccessible
 
   // Override get_accParent for e10s
@@ -52,9 +61,6 @@ class MsaaDocAccessible : public DocAccessible {
    * This provides a mapping from 32 bit id to accessible objects.
    */
   nsTHashMap<nsUint32HashKey, AccessibleWrap*> mIDToAccessibleMap;
-
- private:
-  DocAccessible* DocAcc();
 };
 
 }  // namespace a11y