Add View::AddedToWidget and RemovedFromWidget.

ui/views/view_unittest.cc

Index: ui/views/view_unittest.cc
diff --git a/ui/views/view_unittest.cc b/ui/views/view_unittest.cc
index e1b6710554409fd3a4dce25fd321645b93530eff..3f3a7af9a81cefa3b89b1627664867d89551e36e 100644
--- a/ui/views/view_unittest.cc
+++ b/ui/views/view_unittest.cc
@@ -3335,6 +3335,93 @@ TEST_F(ViewTest, ViewHierarchyChanged) {
   EXPECT_EQ(v2.get(), v4->add_details().move_view);
 }
 
+class WidgetObserverView : public View {
+ public:
+  WidgetObserverView();
+  ~WidgetObserverView() override;
+
+  void ResetTestState();
+
+  bool was_added_to_widget() { return was_added_to_widget_; }
+  bool was_removed_from_widget() { return was_removed_from_widget_; }
+
+ private:
+  void AddedToWidget() override;
+  void RemovedFromWidget() override;
+
+  bool was_added_to_widget_;

[sky, 2017/02/22 17:21:33]

Make these counts, so you know if called more often than you expect.

+  bool was_removed_from_widget_;
+};

[sky, 2017/02/22 17:21:33]

DISALLOW...

+
+WidgetObserverView::WidgetObserverView() {
+  ResetTestState();
+}
+
+WidgetObserverView::~WidgetObserverView() {}
+
+void WidgetObserverView::ResetTestState() {
+  was_added_to_widget_ = false;
+  was_removed_from_widget_ = false;
+}
+
+void WidgetObserverView::AddedToWidget() {
+  was_added_to_widget_ = true;
+}
+
+void WidgetObserverView::RemovedFromWidget() {
+  was_removed_from_widget_ = true;
+}
+
+// Verifies that AddedToWidget and RemovedFromWidget are called for a view when
+// it is added to hierarchy.
+// The tree looks like this:
+// widget
+// +-- root
+//
+// then v1 is added to root:
+//
+//     v1
+//     +-- v2
+//
+// finally v1 is removed from root.
+TEST_F(ViewTest, AddedToRemovedFromWidget) {
+  std::unique_ptr<Widget> widget(new Widget);

[sky, 2017/02/22 17:21:33]

No need for a unique_ptr here, create on stack.

+  Widget::InitParams params = CreateParams(Widget::InitParams::TYPE_POPUP);
+  params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.bounds = gfx::Rect(50, 50, 650, 650);
+  widget->Init(params);
+
+  View* root = widget->GetRootView();
+
+  WidgetObserverView v1;
+  WidgetObserverView v2;
+  v1.set_owned_by_client();
+  v2.set_owned_by_client();
+
+  v1.AddChildView(&v2);
+  EXPECT_FALSE(v2.was_added_to_widget());
+  EXPECT_FALSE(v2.was_removed_from_widget());
+
+  root->AddChildView(&v1);
+  EXPECT_TRUE(v1.was_added_to_widget());
+  EXPECT_FALSE(v1.was_removed_from_widget());
+  EXPECT_TRUE(v2.was_added_to_widget());
+  EXPECT_FALSE(v2.was_removed_from_widget());
+
+  v1.ResetTestState();
+  v2.ResetTestState();
+
+  root->RemoveChildView(&v1);
+  EXPECT_FALSE(v1.was_added_to_widget());
+  EXPECT_TRUE(v1.was_removed_from_widget());
+  EXPECT_FALSE(v2.was_added_to_widget());
+  EXPECT_TRUE(v2.was_removed_from_widget());
+
+  v2.ResetTestState();
+  v1.RemoveChildView(&v2);
+  EXPECT_FALSE(v2.was_removed_from_widget());
+}
+
 // Verifies if the child views added under the root are all deleted when calling
 // RemoveAllChildViews.
 // The tree looks like this: