diff --git a/dom/ipc/ContentParent.cpp b/dom/ipc/ContentParent.cpp
index 9bba64a1c62b..7bc85544bd35 100644
--- a/dom/ipc/ContentParent.cpp
+++ b/dom/ipc/ContentParent.cpp
@@ -34,6 +34,9 @@
 #include "IHistory.h"
 #include "imgIContainer.h"
 #include "mozIApplication.h"
+#if defined(XP_WIN) && defined(ACCESSIBILITY)
+#include "mozilla/a11y/AccessibleWrap.h"
+#endif
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/StyleSheetInlines.h"
 #include "mozilla/DataStorage.h"
@@ -1954,6 +1957,10 @@ ContentParent::ActorDestroy(ActorDestroyReason why)
   }
 
   mBlobURLs.Clear();
+
+#if defined(XP_WIN32) && defined(ACCESSIBILITY)
+  a11y::AccessibleWrap::ReleaseContentProcessIdFor(ChildID());
+#endif
 }
 
 void
@@ -5348,6 +5355,18 @@ ContentParent::RecvUnstoreAndBroadcastBlobURLUnregistration(const nsCString& aUR
   return true;
 }
 
+bool
+ContentParent::RecvGetA11yContentId(uint32_t* aContentId)
+{
+#if defined(XP_WIN32) && defined(ACCESSIBILITY)
+  *aContentId = a11y::AccessibleWrap::GetContentProcessIdFor(ChildID());
+  MOZ_ASSERT(*aContentId);
+  return true;
+#else
+  return false;
+#endif
+}
+
 } // namespace dom
 } // namespace mozilla
 
diff --git a/dom/ipc/ContentParent.h b/dom/ipc/ContentParent.h
index 924fe3804652..b7fe9809ce39 100644
--- a/dom/ipc/ContentParent.h
+++ b/dom/ipc/ContentParent.h
@@ -565,6 +565,9 @@ public:
   virtual bool
   RecvUnstoreAndBroadcastBlobURLUnregistration(const nsCString& aURI) override;
 
+  virtual bool
+  RecvGetA11yContentId(uint32_t* aContentId) override;
+
   virtual int32_t Pid() const override;
 
   // Use the PHangMonitor channel to ask the child to repaint a tab.
diff --git a/dom/ipc/PContent.ipdl b/dom/ipc/PContent.ipdl
index fc7472e31b51..e8632281eefc 100644
--- a/dom/ipc/PContent.ipdl
+++ b/dom/ipc/PContent.ipdl
@@ -1236,6 +1236,8 @@ parent:
     async AccumulateChildHistogram(Accumulation[] accumulations);
     async AccumulateChildKeyedHistogram(KeyedAccumulation[] accumulations);
 
+     sync GetA11yContentId() returns (uint32_t aContentId);
+
 both:
      async AsyncMessage(nsString aMessage, CpowEntry[] aCpows,
                         Principal aPrincipal, ClonedMessageData aData);