Minor fixes for WidgetRemovalsObserver::OnWillRemoveView

ui/views/widget/widget_unittest.cc

Index: ui/views/widget/widget_unittest.cc
diff --git a/ui/views/widget/widget_unittest.cc b/ui/views/widget/widget_unittest.cc
index 41bbe8198d7b40b9136deaf3ae068bb795c3be87..ac5d2d12b8dee7284b92a0db89cf84c3e9b89521 100644
--- a/ui/views/widget/widget_unittest.cc
+++ b/ui/views/widget/widget_unittest.cc
@@ -29,6 +29,7 @@
 #include "ui/views/widget/native_widget_delegate.h"
 #include "ui/views/widget/root_view.h"
 #include "ui/views/widget/widget_deletion_observer.h"
+#include "ui/views/widget/widget_removals_observer.h"
 #include "ui/views/window/dialog_delegate.h"
 #include "ui/views/window/native_frame_view.h"
 
@@ -3401,5 +3402,46 @@ TEST_F(WidgetTest, OnDeviceScaleFactorChanged) {
   EXPECT_EQ(scale_factor, view->last_scale_factor());
 }
 
+namespace {
+
+class TestWidgetRemovalsObserver : public WidgetRemovalsObserver {
+ public:
+  TestWidgetRemovalsObserver() {}
+  ~TestWidgetRemovalsObserver() override {}
+
+  void OnWillRemoveView(Widget* widget, View* view) override {
+    removed_views_.insert(view);
+  }
+
+  bool DidRemoveView(View* view) {
+    return removed_views_.find(view) != removed_views_.end();
+  }
+
+ private:
+  std::set<View*> removed_views_;
+};
+
+}
+
+// Test that WidgetRemovalsObserver::OnWillRemoveView is called on every
+// deleted view.
+TEST_F(WidgetTest, WidgetRemovalsObserver) {
+  WidgetAutoclosePtr widget(CreateTopLevelPlatformWidget());
+  TestWidgetRemovalsObserver removals_observer;
+  widget->AddRemovalsObserver(&removals_observer);
+
+  View* parent = new View();
+  widget->client_view()->AddChildView(parent);
+
+  View* child = new View();
+  parent->AddChildView(child);
+
+  widget->client_view()->RemoveChildView(parent);
+  EXPECT_TRUE(removals_observer.DidRemoveView(parent));
+  EXPECT_TRUE(removals_observer.DidRemoveView(child));
+
+  widget->RemoveRemovalsObserver(&removals_observer);
+}
+
 }  // namespace test
 }  // namespace views