[WebPayments] Implement state transitions in desktop WebPayments dialog.

chrome/browser/ui/views/payments/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 "chrome/browser/ui/views/payments/payment_request_dialog.h"
+
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/payments/payment_request_impl.h"
-#include "chrome/browser/ui/views/payments/payment_request_dialog.h"
+#include "chrome/browser/ui/views/payments/order_summary_state.h"
+#include "chrome/browser/ui/views/payments/payment_sheet_state.h"
+#include "chrome/browser/ui/views/payments/view_stack.h"
 #include "components/constrained_window/constrained_window_views.h"
 #include "content/public/browser/browser_thread.h"
 #include "ui/views/layout/fill_layout.h"
 
 namespace chrome {
 
 void ShowPaymentRequestDialog(payments::PaymentRequestImpl* impl) {
     constrained_window::ShowWebModalDialogViews(
         new payments::PaymentRequestDialog(impl), impl->web_contents());
 }
 
 }
 
 namespace payments {
 
 PaymentRequestDialog::PaymentRequestDialog(PaymentRequestImpl* impl)
-    : impl_(impl),
-      label_(new views::Label(base::ASCIIToUTF16("Payments dialog"))) {
+    : impl_(impl) {
   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);
+  view_stack_.reset(new ViewStack(std::move(initial_state)));

[sky, 2016/12/12 01:54:32]

Can you elaborate on why ViewStack can't operate solely on View? It seems like
ViewStack could contain a stack of Views, and not a stack of ViewStackState. If
you need to associate extra data with the Views can't they be done here and not
in ViewStack? I'm suggesting the API for ViewStack is:
PushState(std::unique_ptr<View> view);
PopState().

[anthonyvd, 2016/12/12 17:01:56]

I felt like encapsulating event handling in the states would make the dialog
code cleaner (for example, it avoids huge functions that switch on button->tag()
to figure out what to do). However now that ViewStack is independent of
payments, the interface you suggest probably makes more sense. The added
complexity + forcing callers to subclass ViewStackState isn't worth the slightly
more separated code.

The latest patchset implements that interface, let me know what you think!

+  view_stack_->set_owned_by_client();
+  AddChildView(view_stack_.get());
 }
 
 PaymentRequestDialog::~PaymentRequestDialog() {}
 
 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);
   impl_->Cancel();
   return true;
 }
 
+void PaymentRequestDialog::OnOrderSummaryClicked() {
+  std::unique_ptr<OrderSummaryState> order_summary =
+      base::MakeUnique<OrderSummaryState>();
+  order_summary->AddObserver(this);
+  view_stack_->PushState(std::move(order_summary));
+}
+
+void PaymentRequestDialog::OnBackClicked() {
+  view_stack_->PopState();
+}
+
 }  // namespace payments