add experiment support and add urlprefix for autocheckout.

chrome/browser/autofill/form_structure.cc

Index: chrome/browser/autofill/form_structure.cc
diff --git a/chrome/browser/autofill/form_structure.cc b/chrome/browser/autofill/form_structure.cc
index 39cdf5f838cac4dbdeadb9026d3ef25c7e929824..4174bbf5f20facb714cdabcc706e1da30ee75e81 100644
--- a/chrome/browser/autofill/form_structure.cc
+++ b/chrome/browser/autofill/form_structure.cc
@@ -40,7 +40,9 @@ const char kAttributeClientVersion[] = "clientversion";
 const char kAttributeDataPresent[] = "datapresent";
 const char kAttributeFormSignature[] = "formsignature";
 const char kAttributeSignature[] = "signature";
-const char kAcceptedFeatures[] = "e"; // e=experiments
+const char kAttributeUrlprefix[] = "urlprefix";
+const char kAcceptedFeatureExperiment[] = "e"; // e=experiments
+const char kAcceptedFeatureAutocheckout[] = "a"; // a=autocheckout
 const char kClientVersion[] = "6.1.1715.1442/en (GGLL)";
 const char kXMLDeclaration[] = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";
 const char kXMLElementAutofillQuery[] = "autofillquery";
@@ -375,9 +377,8 @@ bool FormStructure::EncodeQueryRequest(
       (buzz::QName(kXMLElementAutofillQuery)));
   autofill_request_xml.SetAttr(buzz::QName(kAttributeClientVersion),
                                kClientVersion);
-  autofill_request_xml.SetAttr(buzz::QName(kAttributeAcceptedFeatures),
-                               kAcceptedFeatures);
 
+  std::string autocheckout_urlprefix;
   // Some badly formatted web sites repeat forms - detect that and encode only
   // one form as returned data would be the same for all the repeated forms.
   std::set<std::string> processed_forms;
@@ -397,6 +398,13 @@ bool FormStructure::EncodeQueryRequest(
                                   encompassing_xml_element.get()))
       continue;  // Malformed form, skip it.
 
+    if ((*it)->autocheckout_enabled_ && autocheckout_urlprefix.empty()) {
+      GURL::Replacements replacements;
+      replacements.ClearQuery();
+      autocheckout_urlprefix = (*it)->source_url()
+          .ReplaceComponents(replacements).spec();
+    }
+
     autofill_request_xml.AddElement(encompassing_xml_element.release());
     encoded_signatures->push_back(signature);
   }
@@ -404,6 +412,16 @@ bool FormStructure::EncodeQueryRequest(
   if (!encoded_signatures->size())
     return false;
 
+  if (autocheckout_urlprefix.empty()) {
+    autofill_request_xml.SetAttr(buzz::QName(kAttributeAcceptedFeatures),
+                                 kAcceptedFeatureExperiment);
+  } else {
+    autofill_request_xml.SetAttr(buzz::QName(kAttributeAcceptedFeatures),
+                                 kAcceptedFeatureAutocheckout);
+    autofill_request_xml.SetAttr(buzz::QName(kAttributeUrlprefix),
+                                 autocheckout_urlprefix);
+  }
+
   // Obtain the XML structure as a string.
   *encoded_xml = kXMLDeclaration;
   *encoded_xml += autofill_request_xml.Str().c_str();