[Payments] Put Web Payments feature on desktop behind flag

chrome/browser/payments/site_per_process_payments_browsertest.cc

Index: chrome/browser/payments/site_per_process_payments_browsertest.cc
diff --git a/chrome/browser/payments/site_per_process_payments_browsertest.cc b/chrome/browser/payments/site_per_process_payments_browsertest.cc
index 330c4a3b8fda7b723f0267f273f962e836b87c22..cc1448e5c77bb41c8b9b5ee55a96b8648cff27f9 100644
--- a/chrome/browser/payments/site_per_process_payments_browsertest.cc
+++ b/chrome/browser/payments/site_per_process_payments_browsertest.cc
@@ -12,6 +12,7 @@
 #include "content/public/browser/render_view_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
+#include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/test/browser_test_utils.h"
 #include "content/public/test/test_utils.h"
@@ -34,6 +35,8 @@ class SitePerProcessPaymentsBrowserTest : public InProcessBrowserTest {
     command_line->AppendSwitch(switches::kIgnoreCertificateErrors);
     command_line->AppendSwitch(
         switches::kEnableExperimentalWebPlatformFeatures);
+    command_line->AppendSwitchASCII(switches::kEnableFeatures,
+                                    features::kWebPayments.name);
     // Append --site-per-process flag.
     content::IsolateAllSitesForTesting(command_line);
   }