Bug 1821972 part 1: Remove/replace the few remaining ipc/mscom uses in a11y code. r=nlapre

Regarding LazyInstantiator::ResolveDispatch, we already had code in MsaaAccessible to get the IAccessible typelib.
mscom::RegisterTypelib has a lot of dependencies and it doesn't make sense to keep it for this one use case we can already support another way.

Differential Revision: https://phabricator.services.mozilla.com/D177966

accessible/windows/msaa/LazyInstantiator.cpp

@@ -12,7 +12,6 @@
 #include "mozilla/a11y/Platform.h"
 #include "mozilla/Assertions.h"
 #include "mozilla/mscom/ProcessRuntime.h"
-#include "mozilla/mscom/Registration.h"
 #include "mozilla/UniquePtr.h"
 #include "mozilla/WinHeaderOnlyUtils.h"
 #include "MsaaRootAccessible.h"
@@ -449,25 +448,16 @@ LazyInstantiator::ResolveDispatch() {
     return S_OK;
   }
 
-  // The IAccessible typelib is embedded in oleacc.dll's resources.
-  auto typelib = mscom::RegisterTypelib(
-      L"oleacc.dll", mscom::RegistrationFlags::eUseSystemDirectory);
-  if (!typelib) {
+  // Extract IAccessible's type info
+  RefPtr<ITypeInfo> accTypeInfo = MsaaAccessible::GetTI(LOCALE_USER_DEFAULT);
+  if (!accTypeInfo) {
     return E_UNEXPECTED;
   }
 
-  // Extract IAccessible's type info
-  RefPtr<ITypeInfo> accTypeInfo;
-  HRESULT hr =
-      typelib->GetTypeInfoForGuid(IID_IAccessible, getter_AddRefs(accTypeInfo));
-  if (FAILED(hr)) {
-    return hr;
-  }
-
   // Now create the standard IDispatch for IAccessible
-  hr = ::CreateStdDispatch(static_cast<IAccessible*>(this),
-                           static_cast<IAccessible*>(this), accTypeInfo,
-                           getter_AddRefs(mStdDispatch));
+  HRESULT hr = ::CreateStdDispatch(static_cast<IAccessible*>(this),
+                                   static_cast<IAccessible*>(this), accTypeInfo,
+                                   getter_AddRefs(mStdDispatch));
   if (FAILED(hr)) {
     return hr;
   }

accessible/windows/msaa/LazyInstantiator.h

@@ -8,7 +8,6 @@
 #define mozilla_a11y_LazyInstantiator_h
 
 #include "IUnknownImpl.h"
-#include "mozilla/mscom/Ptr.h"
 #include "mozilla/RefPtr.h"
 #include "nsString.h"
 

accessible/windows/msaa/MsaaAccessible.h

@@ -54,6 +54,11 @@ class MsaaAccessible : public ia2Accessible,
 
   static MsaaAccessible* GetFrom(Accessible* aAcc);
 
+  /**
+   * Creates ITypeInfo for LIBID_Accessibility if it's needed and returns it.
+   */
+  static ITypeInfo* GetTI(LCID lcid);
+
   DECL_IUNKNOWN
 
   // IAccessible
@@ -180,10 +185,6 @@ class MsaaAccessible : public ia2Accessible,
   };
 
  private:
-  /**
-   * Creates ITypeInfo for LIBID_Accessibility if it's needed and returns it.
-   */
-  static ITypeInfo* GetTI(LCID lcid);
   static ITypeInfo* gTypeInfo;
 };