[Payments] Implements the credit card editor for Desktop UI

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

 // 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.
 
 #ifndef CHROME_BROWSER_UI_VIEWS_PAYMENTS_VIEW_STACK_H_
 #define CHROME_BROWSER_UI_VIEWS_PAYMENTS_VIEW_STACK_H_
 
 #include "ui/views/view.h"
 #include "ui/views/animation/bounds_animator.h"
 #include "ui/views/animation/bounds_animator_observer.h"
 
+namespace payments {
+class PaymentRequestInteractiveTestBase;
+}  // namespace payments
+

[please use gerrit instead, 2017/02/02 20:19:03]

Is this forward declaration necessary?

[Mathieu, 2017/02/03 02:18:57]

Yes :\ It was cryptic to me why it was needed; someone explained that without
it, the "friend class" statement below does not know what the symbol is, and
compiler may think we are just declaring an inner class. 

 // This view represents a stack of views that slide in over one another from
 // left to right. It manages the animation and lifetime of views that are
 // pushed and popped on it. To use this class, add it to a view hierarchy, and
 // call Push/Pop to animate views in and out.
 class ViewStack : public views::BoundsAnimatorObserver,
                   public views::View {
  public:
   ViewStack();
   ~ViewStack() override;
 
@@ skipping 14 matching lines @@
   void Layout() override;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(
       ViewStackTest, TestPopStateRemovesChildViewAndCleansUpState);
   FRIEND_TEST_ALL_PREFIXES(ViewStackTest, TestDeletingViewCleansUpState);
   FRIEND_TEST_ALL_PREFIXES(ViewStackTest, TestInitialStateAddedAsChildView);
   FRIEND_TEST_ALL_PREFIXES(ViewStackTest, TestPushStateAddsViewToChildren);
   FRIEND_TEST_ALL_PREFIXES(ViewStackTest, TestLayoutUpdatesAnimations);
   friend class ViewStackTest;
+  friend class payments::PaymentRequestInteractiveTestBase;
 
   // Returns the top state of the stack, used in tests.
   views::View* top() { return stack_.back().get(); }
 
   void UpdateAnimatorBounds(
       views::BoundsAnimator* animator, const gfx::Rect& target);
 
   // views::BoundsAnimatorObserver:
   void OnBoundsAnimatorProgressed(views::BoundsAnimator* animator) override {}
   void OnBoundsAnimatorDone(views::BoundsAnimator* animator) override;
 
   std::vector<std::unique_ptr<views::View>> stack_;
 
   std::unique_ptr<views::BoundsAnimator> slide_in_animator_;
   std::unique_ptr<views::BoundsAnimator> slide_out_animator_;
 
   DISALLOW_COPY_AND_ASSIGN(ViewStack);
 };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_PAYMENTS_VIEW_STACK_H_