Hide NativeViewHostAura correctly.

This CL fixes an issue where the NativeViewHostAura clipping window would
not be hidden correctly and steal mouse events from the experimental app
list. This CL simply hides the clipping window when the NativeViewHost
is hidden.

BUG=408877

Review URL: https://codereview.chromium.org/517143003

Cr-Commit-Position: refs/heads/master@{#293125}

ui/views/controls/native/native_view_host_aura.cc

@@ -165,6 +165,7 @@ void NativeViewHostAura::ShowWidget(int x, int y, int w, int h) {
 
 void NativeViewHostAura::HideWidget() {
   host_->native_view()->Hide();
+  clipping_window_.Hide();
 }
 
 void NativeViewHostAura::SetFocus() {

ui/views/controls/native/native_view_host_aura_unittest.cc

@@ -374,4 +374,24 @@ TEST_F(NativeViewHostAuraTest, Attach) {
   DestroyHost();
 }
 
+// Ensure the clipping window is hidden with the native view. This is a
+// regression test for https://crbug.com/408877.
+TEST_F(NativeViewHostAuraTest, SimpleShowAndHide) {
+  CreateHost();
+
+  toplevel()->SetBounds(gfx::Rect(20, 20, 100, 100));
+  toplevel()->Show();
+
+  host()->SetBounds(10, 10, 80, 80);
+  EXPECT_TRUE(clipping_window()->IsVisible());
+  EXPECT_TRUE(child()->IsVisible());
+
+  host()->SetVisible(false);
+  EXPECT_FALSE(clipping_window()->IsVisible());
+  EXPECT_FALSE(child()->IsVisible());
+
+  DestroyHost();
+  DestroyTopLevel();
+}
+
 }  // namespace views