Updated TestChildModalParent to use AddedToWidget()

Removed the use of ViewHierarchyChanged() to update native view
properties when added to a view hierarchy. Changed to use
AddedToWidget() instead.

Currently the logic in ViewHierarchyChanged() requires the view
be in a Widget hierarchy. This should not be assumed in
ViewHierarchyChanged(). Instead, having the logic in AddedToWidget()
helps to make the assumptions more clear.

Bug: 1083822
Change-Id: Ia393fd0141a863212e5c9e30e364fbc4d2b2d7d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2206215Reviewed-by: Robert Flack <flackr@chromium.org>
Commit-Queue: Thomas Lukaszewicz <tluk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#771036}

ash/wm/test_child_modal_parent.cc

@@ -138,12 +138,11 @@ void TestChildModalParent::Layout() {
   host_->SetBounds(x(), running_y, width(), height() - running_y);
 }
 
-void TestChildModalParent::ViewHierarchyChanged(
-    const views::ViewHierarchyChangedDetails& details) {
-  if (details.is_add && details.child == this) {
-    host_->Attach(modal_parent_->GetNativeView());
-    GetWidget()->GetNativeView()->SetName("Parent");
-  }
+void TestChildModalParent::AddedToWidget() {
+  // The function requires a Widget be present.
+  DCHECK(GetWidget());
+  host_->Attach(modal_parent_->GetNativeView());
+  GetWidget()->GetNativeView()->SetName("Parent");
 }
 
 void TestChildModalParent::ButtonPressed(views::Button* sender,

ash/wm/test_child_modal_parent.h

@@ -42,8 +42,7 @@ class TestChildModalParent : public views::WidgetDelegateView,
  private:
   // Overridden from views::View:
   void Layout() override;
-  void ViewHierarchyChanged(
-      const views::ViewHierarchyChangedDetails& details) override;
+  void AddedToWidget() override;
 
   // Overridden from ButtonListener:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;