Do not hide shadow underlay for max/fullscreen state even if the client disables the shadow.

components/exo/shell_surface_unittest.cc

Index: components/exo/shell_surface_unittest.cc
diff --git a/components/exo/shell_surface_unittest.cc b/components/exo/shell_surface_unittest.cc
index 5e300222acbaa3cf826be1ba02d395b5d36d110a..ba0a3030ec3fc0a6b33009ec76a211bce66fb927 100644
--- a/components/exo/shell_surface_unittest.cc
+++ b/components/exo/shell_surface_unittest.cc
@@ -829,6 +829,20 @@ TEST_F(ShellSurfaceTest, ShadowStartMaximized) {
   ASSERT_TRUE(shell_surface->shadow_underlay());
   EXPECT_TRUE(shell_surface->shadow_underlay()->IsVisible());
 
+  shell_surface->SetRectangularSurfaceShadow(gfx::Rect(0, 0, 0, 0));
+  // Underlay should be created even without shadow.
+  ASSERT_TRUE(shell_surface->shadow_underlay());
+  EXPECT_TRUE(shell_surface->shadow_underlay()->IsVisible());
+  shell_surface->SetRectangularShadowEnabled(false);
+  surface->Commit();
+  // Underlay should be created even without shadow.
+  ASSERT_TRUE(shell_surface->shadow_underlay());
+  EXPECT_TRUE(shell_surface->shadow_underlay()->IsVisible());
+
+  shell_surface->SetRectangularShadowEnabled(true);
+  shell_surface->SetRectangularSurfaceShadow(gfx::Rect(10, 10, 100, 100));
+  surface->Commit();
+
   // Restore the window and make sure the shadow is created, visible and
   // has the latest bounds.
   widget->Restore();