[Web Payments] Add PopMany and Size functions to ViewStack

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 6a8ab76658f41264752d18da175506040c796356..508c1fdaeeb7b8d49aa066e148c5cd5d383ed152 100644
--- a/chrome/browser/ui/views/payments/view_stack.cc
+++ b/chrome/browser/ui/views/payments/view_stack.cc
@@ -59,6 +59,20 @@ void ViewStack::Pop() {
       stack_.back().get(), destination);
 }
 
+void ViewStack::PopMany(int n) {
+  DCHECK_LT(static_cast<size_t>(n), size());  // The stack can never be empty.

[Mathieu, 2017/04/13 16:55:23]

how does Pop handle popping the last view?

[anthonyvd, 2017/04/13 20:22:58]

It doesn't. The view would animate out but hit "DCHECK(!stack_.empty()) <<
"State stack should never be empty";" after removing it. This DCHECK here
ensures that we're always calling PopMany such that there's still at least one
view remaining on the stack.

+
+  // Erase N - 1 elements now, the last one will be erased when its animation
+  // completes
+  stack_.erase(stack_.end() - n, stack_.end() - 1);
+
+  Pop();
+}
+
+size_t ViewStack::size() const {
+  return stack_.size();
+}
+
 bool ViewStack::CanProcessEventsWithinSubtree() const {
   return !slide_in_animator_->IsAnimating() &&
          !slide_out_animator_->IsAnimating();