[WebPayments] Setting hidden views in view stack invisible

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/views/payments/view_stack.h"
 
 #include <memory>
 #include <utility>
 
 #include "base/memory/ptr_util.h"
@@ skipping 31 matching lines @@
 
     // Animate the new view to be right on top of this one.
     slide_in_animator_->AnimateViewTo(view.get(), destination);
   } else {
     view->SetBoundsRect(destination);
     view->Layout();
     AddChildView(view.get());
   }
 
   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));
   RequestFocus();
 }
 
 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);
 }
 
 void ViewStack::PopMany(int n) {
   DCHECK_LT(static_cast<size_t>(n), size());  // The stack can never be empty.
 
   size_t pre_size = stack_.size();
   // Erase N - 1 elements now, the last one will be erased when its animation
   // completes
@@ skipping 50 matching lines @@
 
 void ViewStack::OnBoundsAnimatorDone(views::BoundsAnimator* animator) {
   // This should only be called from slide_out_animator_ when the views going
   // out are done animating.
   DCHECK_EQ(animator, slide_out_animator_.get());
 
   stack_.pop_back();
   DCHECK(!stack_.empty()) << "State stack should never be empty";
   RequestFocus();
 }