Plumb native AppWindow input region through to window shape under Aura.

ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
index 180614e955525046fbbfc4e2a0b5b810d681ca8a..884608768bf65683f5d04ca8c0d967755c6f8e3f 100644
--- a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
@@ -430,11 +430,18 @@ gfx::Rect DesktopRootWindowHostX11::GetWorkAreaBoundsInScreen() const {
 }
 
 void DesktopRootWindowHostX11::SetShape(gfx::NativeRegion native_region) {
-  SkPath path;
-  native_region->getBoundaryPath(&path);
-  Region region = gfx::CreateRegionFromSkPath(path);
-  XShapeCombineRegion(xdisplay_, xwindow_, ShapeBounding, 0, 0, region, false);
-  XDestroyRegion(region);
+  if (native_region) {
+    SkPath path;
+    native_region->getBoundaryPath(&path);
+    Region region = gfx::CreateRegionFromSkPath(path);
+    XShapeCombineRegion(
+        xdisplay_, xwindow_, ShapeBounding, 0, 0, region, false);
+    XDestroyRegion(region);
+  } else {
+    ResetWindowRegion();
+  }
+
+  delete native_region;
 }
 
 void DesktopRootWindowHostX11::Activate() {