Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

components/update_client/crx_update_item.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_CRX_UPDATE_ITEM_H_
 #define COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 53 matching lines @@
     kUpdated,
     kUpToDate,
     kNoUpdate,
     kLastStatus
   };
 
   // Call CrxUpdateService::ChangeItemState to change |status|. The function may
   // enforce conditions or notify observers of the change.
   Status status;
 
+  // True if the component was recently unregistered and will be uninstalled
+  // soon (after the currently operation is finished, if there is one).
+  bool unregistered;
+
   std::string id;
   CrxComponent component;
 
   base::Time last_check;
 
   // A component can be made available for download from several urls.
   std::vector<GURL> crx_urls;
   std::vector<GURL> crx_diffurls;
 
   // The from/to version and fingerprint values.
@@ skipping 36 matching lines @@
     bool operator()(CrxUpdateItem* item) const { return item->id == id_; }
 
    private:
     const std::string& id_;
   };
 };
 
 }  // namespace update_client
 
 #endif  // COMPONENTS_UPDATE_CLIENT_CRX_UPDATE_ITEM_H_