Add support for Omaha cohorts to the component updater.

components/update_client/update_response.h

 // 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.
 
 #ifndef COMPONENTS_UPDATE_CLIENT_UPDATE_RESPONSE_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_RESPONSE_H_
 
+#include <map>
+#include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "url/gurl.h"
 
 namespace update_client {
 
 // Parses responses for the update protocol version 3.
 // (https://github.com/google/omaha/blob/wiki/ServerProtocolV3.md)
@@ skipping 74 matching lines @@
     ~Result();
 
     std::string extension_id;
 
     // The list of fallback urls, for full and diff updates respectively.
     // These urls are base urls; they don't include the filename.
     std::vector<GURL> crx_urls;
     std::vector<GURL> crx_diffurls;
 
     Manifest manifest;
+
+    // The server has instructed the client to set its [key] to [value] for each
+    // key-value pair in this string.
+    std::map<std::string, std::string> cohort_attrs;
+
+    // The following are the only allowed keys in |cohort_attrs|.
+    static const char* kCohort;

[Sorin Jianu, 2016/08/23 00:20:03]

can we use static const char kCohort[] ?

[waffles, 2016/08/23 00:36:18]

Done.

+    static const char* kCohortHint;
+    static const char* kCohortName;
   };
 
   static const int kNoDaystart = -1;
   struct Results {
     Results();
     Results(const Results& other);
     ~Results();
 
     // This will be >= 0, or kNoDaystart if the <daystart> tag was not present.
     int daystart_elapsed_seconds;
@@ skipping 20 matching lines @@
 
   // Adds parse error details to |errors_| string.
   void ParseError(const char* details, ...);
 
   DISALLOW_COPY_AND_ASSIGN(UpdateResponse);
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_UPDATE_RESPONSE_H_