ANGLE: Fix flickering on resize when D3D9 is used

By reverting ANGLE change d3b84ab51db09de238459b0dff2e8420c09aabf3
we get rid of the flickering that happens on resize when D3D9 is
used. The issue that was fixed there is not relevant in Qt's
context so it is safe to revert the change.

Task-number: QTBUG-59893
Change-Id: I9306314b892612fbd1f7a058a2e606aedc0367bb
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/3rdparty/angle/src/libANGLE/renderer/d3d/SurfaceD3D.h b/src/3rdparty/angle/src/libANGLE/renderer/d3d/SurfaceD3D.h
index b925bfc8cc..67d408ddd9 100644
--- a/src/3rdparty/angle/src/libANGLE/renderer/d3d/SurfaceD3D.h
+++ b/src/3rdparty/angle/src/libANGLE/renderer/d3d/SurfaceD3D.h
@@ -82,6 +82,9 @@ class SurfaceD3D : public SurfaceImpl
     egl::Error resetSwapChain(int backbufferWidth, int backbufferHeight);
     egl::Error resizeSwapChain(int backbufferWidth, int backbufferHeight);
 
+    void subclassWindow();
+    void unsubclassWindow();
+
     RendererD3D *mRenderer;
     egl::Display *mDisplay;
 
@@ -93,6 +96,7 @@ class SurfaceD3D : public SurfaceImpl
 
     SwapChainD3D *mSwapChain;
     bool mSwapIntervalDirty;
+    bool mWindowSubclassed;        // Indicates whether we successfully subclassed mWindow for WM_RESIZE hooking
 
     NativeWindow mNativeWindow;   // Handler for the Window that the surface is created for.
     EGLint mWidth;