Add support for Omaha cohorts to the component updater.

components/update_client/update_response.h

Index: components/update_client/update_response.h
diff --git a/components/update_client/update_response.h b/components/update_client/update_response.h
index 6c0ea9bd9351497a793aa5bc5d1cf7cfc464189e..bfe61b57173918287a1f106580be9a6b1001dbb0 100644
--- a/components/update_client/update_response.h
+++ b/components/update_client/update_response.h
@@ -5,6 +5,7 @@
 #ifndef COMPONENTS_UPDATE_CLIENT_UPDATE_RESPONSE_H_
 #define COMPONENTS_UPDATE_CLIENT_UPDATE_RESPONSE_H_
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -89,6 +90,7 @@ class UpdateResponse {
 
     Result();
     Result(const Result& other);
+    UpdateResponse::Result& operator=(const Result& other);
     ~Result();
 
     std::string extension_id;
@@ -99,6 +101,12 @@ class UpdateResponse {
     std::vector<GURL> crx_diffurls;
 
     Manifest manifest;
+
+    // When non-null, the server has instructed the client to set its cohort/
+    // cohorthint/cohortname to this string.
+    std::unique_ptr<std::string> cohort;
+    std::unique_ptr<std::string> cohort_hint;
+    std::unique_ptr<std::string> cohort_name;
   };
 
   static const int kNoDaystart = -1;