Fix the broken XML parser due to version mismatch.

components/update_client/update_response.cc

 // Copyright 2014 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 "components/update_client/update_response.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/version.h"
 #include "libxml/tree.h"
 #include "third_party/libxml/chromium/libxml_utils.h"
 
 namespace update_client {
 
-static const char* kExpectedResponseProtocol = "3.0";
 const char UpdateResponse::Result::kCohort[] = "cohort";
 const char UpdateResponse::Result::kCohortHint[] = "cohorthint";
 const char UpdateResponse::Result::kCohortName[] = "cohortname";
 
 UpdateResponse::UpdateResponse() = default;
 UpdateResponse::~UpdateResponse() = default;
 
 UpdateResponse::Results::Results() = default;
 UpdateResponse::Results::Results(const Results& other) = default;
 UpdateResponse::Results::~Results() = default;
@@ skipping 326 matching lines @@
     ParseError("Missing root node");
     return false;
   }
 
   if (!TagNameEquals(root, "response")) {
     ParseError("Missing response tag");
     return false;
   }
 
   // Check for the response "protocol" attribute.
-  if (GetAttribute(root, "protocol") != kExpectedResponseProtocol) {
+  const auto protocol = GetAttribute(root, "protocol");
+  if (protocol != kProtocolVersion) {
     ParseError(
         "Missing/incorrect protocol on response tag "
-        "(expected '%s')",
-        kExpectedResponseProtocol);
+        "(expected '%s', found '%s')",
+        kProtocolVersion, protocol.c_str());
     return false;
   }
 
   // Parse the first <daystart> if it is present.
   std::vector<xmlNode*> daystarts = GetChildren(root, "daystart");
   if (!daystarts.empty()) {
     xmlNode* first = daystarts[0];
     std::string elapsed_seconds = GetAttribute(first, "elapsed_seconds");
     int parsed_elapsed = kNoDaystart;
     if (base::StringToInt(elapsed_seconds, &parsed_elapsed)) {
@@ skipping 15 matching lines @@
       results_.list.push_back(result);
     } else {
       ParseError("%s", error.c_str());
     }
   }
 
   return true;
 }
 
 }  // namespace update_client