[WebPayments] Implement state transitions in desktop WebPayments dialog.

chrome/browser/payments/ui/payment_request_dialog.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 "base/strings/utf_string_conversions.h"
 #include "chrome/browser/payments/ui/payment_request_dialog.h"
 #include "content/public/browser/browser_thread.h"
+#include "ui/views/animation/bounds_animator_observer.h"
 #include "ui/views/layout/fill_layout.h"
 
 namespace payments {
 
+// Observes the Slide Out state animation and removes the view when it's done
+// being animated, then deletes itself. This takes ownership of the state so
+// it's garanteed to be properly disposed of when the animation is over.
+class SlideOutObserver : public views::BoundsAnimatorObserver {
+ public:
+  SlideOutObserver(std::unique_ptr<PaymentDialogState> state_animating_out,
+                   views::View* parent_view)
+    : state_animating_out_(std::move(state_animating_out)),
+      parent_view_(parent_view) {}
+
+  views::View* GetAnimatedView() {
+    return state_animating_out_->GetView();
+  }
+
+ private:
+  // views::BoundsAnimatorObserver:
+  void OnBoundsAnimatorProgressed(views::BoundsAnimator* animator) override {}
+
+  void OnBoundsAnimatorDone(views::BoundsAnimator* animator) override {
+    animator->RemoveObserver(this);
+    parent_view_->RemoveChildView(state_animating_out_->GetView());
+    delete this;
+  }
+
+  std::unique_ptr<PaymentDialogState> state_animating_out_;
+  views::View* parent_view_;
+};
+
 PaymentRequestDialog::PaymentRequestDialog(
     payments::mojom::PaymentRequestClientPtr client)
     : client_(std::move(client)),
-      label_(new views::Label(base::ASCIIToUTF16("Payments dialog"))) {
+      slide_in_animator_(new views::BoundsAnimator(this)),
+      slide_out_animator_(new views::BoundsAnimator(this)) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   SetLayoutManager(new views::FillLayout());
-  AddChildView(label_.get());
+
+  std::unique_ptr<PaymentSheetState> initial_state =
+      base::MakeUnique<PaymentSheetState>();
+  initial_state->AddObserver(this);
+  state_stack_.push(std::move(initial_state));
+
+  AddChildView(state_stack_.top()->GetView());
 }
 
-PaymentRequestDialog::~PaymentRequestDialog() {}
+PaymentRequestDialog::~PaymentRequestDialog() {
+  // Cancel animations to make sure their observer's OnBoundsAnimatorDone is
+  // called.
+  slide_in_animator_->Cancel();
+  slide_out_animator_->Cancel();
+}
+
+void PaymentRequestDialog::PushState(
+    std::unique_ptr<PaymentDialogState> state) {
+  state_stack_.top()->SetInteractable(false);
+
+  // First add the new view out of bounds since it'll slide in from right to
+  // left.
+  state->GetView()->SetPosition(gfx::Point(x() + width(), y()));
+
+  AddChildView(state->GetView());
+  // Animate the new view to be right on top of this one.
+  slide_in_animator_->AnimateViewTo(state->GetView(), bounds());
+
+  // Add the new state to the stack so it can be popped later when navigating
+  // back to the previous screen.
+  state_stack_.push(std::move(state));
+  state_stack_.top()->SetInteractable(true);
+}
+
+void PaymentRequestDialog::PopState() {
+  state_stack_.top()->SetInteractable(false);
+
+  gfx::Rect destination = bounds();
+  destination.Offset(width(), 0);
+
+  // This deletes itself.
+  SlideOutObserver* observer =
+      new SlideOutObserver(std::move(state_stack_.top()), this);
+  slide_out_animator_->AddObserver(observer);
+
+  state_stack_.pop();
+  DCHECK(!state_stack_.empty()) << "State stack should never be empty";
+
+  slide_out_animator_->AnimateViewTo(observer->GetAnimatedView(), destination);
+  state_stack_.top()->SetInteractable(true);
+}
 
 ui::ModalType PaymentRequestDialog::GetModalType() const {
   return ui::MODAL_TYPE_CHILD;
 }
 
 gfx::Size PaymentRequestDialog::GetPreferredSize() const {
-  gfx::Size ps = label_->GetPreferredSize();
-  ps.Enlarge(200, 200);
-  return ps;
+  return gfx::Size(300, 300);
 }
 
 bool PaymentRequestDialog::Cancel() {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   client_->OnError(payments::mojom::PaymentErrorReason::USER_CANCEL);
   return true;
 }
 
+void PaymentRequestDialog::OnOrderSummaryClicked() {
+  std::unique_ptr<OrderSummaryState> order_summary =
+      base::MakeUnique<OrderSummaryState>();
+  order_summary->AddObserver(this);
+  PushState(std::move(order_summary));
+}
+
+void PaymentRequestDialog::OnBackClicked() {
+  PopState();
+}
+
 }  // namespace payments