[WebPayments] Desktop: Adding validation and binding checks

chrome/browser/payments/payment_request_impl.cc

Index: chrome/browser/payments/payment_request_impl.cc
diff --git a/chrome/browser/payments/payment_request_impl.cc b/chrome/browser/payments/payment_request_impl.cc
index 743ab19e26bf7dad196d9ced28889fdbc322523d..b5484f1472a5a0b242d440c087b03b5319c911b1 100644
--- a/chrome/browser/payments/payment_request_impl.cc
+++ b/chrome/browser/payments/payment_request_impl.cc
@@ -8,6 +8,7 @@
 
 #include "base/lazy_instance.h"
 #include "chrome/browser/ui/browser_dialogs.h"
+#include "components/payments/payment_details_validation.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/web_contents.h"
 
@@ -62,10 +63,16 @@ void PaymentRequestImpl::Init(
     payments::mojom::PaymentOptionsPtr options) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   client_ = std::move(client);
+  std::string err_msg;
+  if (!validatePaymentDetails(details, &err_msg)) {

[please use gerrit instead, 2017/01/05 20:11:58]

Also:

LOG(ERROR) << err_msg;

By the way, you may also want to close binding_ and call that
UnassignPaymentRequest thingy.

You don't have to call client_->OnError(), because that tells renderer that an
error occurred. In fact, if this validation error happens in the browser, then
the renderer is already compromised. So there's no need to talk back to it.
Therefore, client_.reset() is sufficient.

+    client_->OnError(payments::mojom::PaymentErrorReason::USER_CANCEL);
+    client_.reset();
+  }
 }
 
 void PaymentRequestImpl::Show() {
-  chrome::ShowPaymentRequestDialog(this);
+  if (client_.is_bound() && binding_.is_bound())
+    chrome::ShowPaymentRequestDialog(this);
 }

[please use gerrit instead, 2017/01/05 20:11:58]

Can you do this? it should ensure that PaymentRequestImpl is deleted, I think.
krb@ originally designed the factory and knows best how it works, but I hear
mathp@ wants to improve on it.

if (!client_.is_bound() || !binding_.is_bound()) {
  payment_request_factory.Get().UnassignPaymentRequest(web_contents_);
  return;
}


// The rest of code.

 
 void PaymentRequestImpl::Cancel() {