Hack to fix MSAA GL -> Vk transition on Windows Viewer

Bug: skia:
Change-Id: I49417789ab43734a1cbb4010281482970579971d
Reviewed-on: https://skia-review.googlesource.com/20505
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
diff --git a/tools/viewer/sk_app/Window.h b/tools/viewer/sk_app/Window.h
index 752dc47..7d0c097 100644
--- a/tools/viewer/sk_app/Window.h
+++ b/tools/viewer/sk_app/Window.h
@@ -191,7 +191,7 @@
     int height();
 
     virtual const DisplayParams& getRequestedDisplayParams() { return fRequestedDisplayParams; }
-    virtual void setRequestedDisplayParams(const DisplayParams&);
+    virtual void setRequestedDisplayParams(const DisplayParams&, bool allowReattach = true);
 
     // Actual parameters in effect, obtained from the native window.
     int sampleCount() const;