Bug 1374792: Modify a11y handler to only invoke IGeckoBackChannel::put_HandlerControl once; r=eeejay

MozReview-Commit-ID: Bxo0IsAuhBh

accessible/ipc/win/handler/AccessibleHandler.cpp

@@ -222,17 +222,12 @@ AccessibleHandler::ReadHandlerPayload(IStream* aStream, REFIID aIid)
     return S_OK;
   }
 
-  long pid = static_cast<long>(::GetCurrentProcessId());
-
-  RefPtr<IHandlerControl> ctl;
-  HRESULT hr = gControlFactory.CreateInstance(nullptr, IID_IHandlerControl,
-                                              getter_AddRefs(ctl));
-  if (SUCCEEDED(hr)) {
-    hr = mCachedData.mGeckoBackChannel->put_HandlerControl(pid, ctl);
-    MOZ_ASSERT(SUCCEEDED(hr));
+  RefPtr<AccessibleHandlerControl> ctl(gControlFactory.GetOrCreateSingleton());
+  if (!ctl) {
+    return E_OUTOFMEMORY;
   }
 
-  return hr;
+  return ctl->Register(WrapNotNull(mCachedData.mGeckoBackChannel));
 }
 
 REFIID

accessible/ipc/win/handler/AccessibleHandlerControl.cpp

@@ -132,7 +132,8 @@ AccessibleHandlerControl::Create(AccessibleHandlerControl** aOutObject)
 }
 
 AccessibleHandlerControl::AccessibleHandlerControl()
-  : mCacheGen(0)
+  : mIsRegistered(false)
+  , mCacheGen(0)
   , mIA2Proxy(mscom::RegisterProxy(L"ia2marshal.dll"))
   , mHandlerProxy(mscom::RegisterProxy())
 {
@@ -189,5 +190,19 @@ AccessibleHandlerControl::GetHandlerTypeInfo(ITypeInfo** aOutTypeInfo)
                                            aOutTypeInfo);
 }
 
+HRESULT
+AccessibleHandlerControl::Register(NotNull<IGeckoBackChannel*> aGecko)
+{
+  if (mIsRegistered) {
+    return S_OK;
+  }
+
+  long pid = static_cast<long>(::GetCurrentProcessId());
+  HRESULT hr = aGecko->put_HandlerControl(pid, this);
+  mIsRegistered = SUCCEEDED(hr);
+  MOZ_ASSERT(mIsRegistered);
+  return hr;
+}
+
 } // namespace a11y
 } // namespace mozilla

accessible/ipc/win/handler/AccessibleHandlerControl.h

@@ -71,10 +71,13 @@ public:
 
   HRESULT GetHandlerTypeInfo(ITypeInfo** aOutTypeInfo);
 
+  HRESULT Register(NotNull<IGeckoBackChannel*> aGecko);
+
 private:
   AccessibleHandlerControl();
   ~AccessibleHandlerControl() = default;
 
+  bool mIsRegistered;
   uint32_t mCacheGen;
   detail::TextChange mTextChange;
   UniquePtr<mscom::RegisteredProxy> mIA2Proxy;