Bug 1356317: Enable off-main-thread compositing on Windows when possible. r=jimm

widget/windows/nsWindow.cpp

@@ -7170,19 +7170,6 @@ nsWindow::IsPopup()
   return mWindowType == eWindowType_popup;
 }
 
-bool
-nsWindow::ShouldUseOffMainThreadCompositing()
-{
-  // We don't currently support using an accelerated layer manager with
-  // transparent windows so don't even try. I'm also not sure if we even
-  // want to support this case. See bug 593471
-  if (!(HasRemoteContent() && gIsPopupCompositingEnabled) && mTransparencyMode == eTransparencyTransparent) {
-    return false;
-  }
-
-  return nsBaseWidget::ShouldUseOffMainThreadCompositing();
-}
-
 void
 nsWindow::WindowUsesOMTC()
 {

widget/windows/nsWindow.h

@@ -301,7 +301,6 @@ public:
   bool                    const DestroyCalled() { return mDestroyCalled; }
 
   bool IsPopup();
-  virtual bool ShouldUseOffMainThreadCompositing() override;
 
   const IMEContext& DefaultIMC() const { return mDefaultIMC; }