[WebPayments] Setting hidden views in view stack invisible

chrome/browser/ui/views/payments/view_stack.cc

Index: chrome/browser/ui/views/payments/view_stack.cc
diff --git a/chrome/browser/ui/views/payments/view_stack.cc b/chrome/browser/ui/views/payments/view_stack.cc
index 6551307e045c4acc5bdb874c61e0c001091d14ae..acc8af4e5d387a7525bfcb0643e76301ac5de88e 100644
--- a/chrome/browser/ui/views/payments/view_stack.cc
+++ b/chrome/browser/ui/views/payments/view_stack.cc
@@ -49,6 +49,12 @@ void ViewStack::Push(std::unique_ptr<views::View> view, bool animate) {
   }
 
   view->set_owned_by_client();
+
+  // If we're pushing on top of an existing view, that view should be marked as
+  // invisible.
+  if (size())

[anthonyvd, 2017/06/16 15:48:21]

Doesn't this make the view invisible before the animation starts? We probably
need to observe the animation and call this when it's over.

+    stack_.back()->SetVisible(false);
+
   // Add the new view to the stack so it can be popped later when navigating
   // back to the previous screen.
   stack_.push_back(std::move(view));
@@ -56,9 +62,15 @@ void ViewStack::Push(std::unique_ptr<views::View> view, bool animate) {
 }
 
 void ViewStack::Pop() {
+  DCHECK_LT(1u, size());  // There must be at least one view left after popping.
+
   gfx::Rect destination = bounds();
   destination.set_origin(gfx::Point(width(), 0));
 
+  // Set the second-to-last view as visible, since it is about to be revealed
+  // when the last view animates out.
+  stack_[size() - 2]->SetVisible(true);
+
   slide_out_animator_->AnimateViewTo(
       stack_.back().get(), destination);
 }