Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

components/component_updater/default_component_installer.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_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_
 #define COMPONENTS_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ skipping 80 matching lines @@
 
   // Registers the component for update checks and installs.
   void Register(ComponentUpdateService* cus);
 
   // Overridden from ComponentInstaller:
   void OnUpdateError(int error) override;
   bool Install(const base::DictionaryValue& manifest,
                const base::FilePath& unpack_path) override;
   bool GetInstalledFile(const std::string& file,
                         base::FilePath* installed_file) override;
+  bool Uninstall() override;
 
  private:
   ~DefaultComponentInstaller() override;
 
   base::FilePath GetInstallDirectory();
   bool InstallHelper(const base::DictionaryValue& manifest,
                      const base::FilePath& unpack_path,
                      const base::FilePath& install_path);
   void StartRegistration(ComponentUpdateService* cus);
   void FinishRegistration(ComponentUpdateService* cus);
   void ComponentReady(scoped_ptr<base::DictionaryValue> manifest);
+  void UninstallOnTaskRunner();
 
   base::Version current_version_;
   std::string current_fingerprint_;
   scoped_ptr<base::DictionaryValue> current_manifest_;
   scoped_ptr<ComponentInstallerTraits> installer_traits_;
   scoped_refptr<base::SequencedTaskRunner> task_runner_;
 
   // Used to post responses back to the main thread. Initialized on the main
   // loop but accessed from the task runner.
   scoped_refptr<base::SingleThreadTaskRunner> main_task_runner_;
 
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(DefaultComponentInstaller);
 };
 
 }  // namespace component_updater
 
 #endif  // COMPONENTS_COMPONENT_UPDATER_DEFAULT_COMPONENT_INSTALLER_H_