Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

chrome/browser/component_updater/recovery_component_installer.cc

Index: chrome/browser/component_updater/recovery_component_installer.cc
diff --git a/chrome/browser/component_updater/recovery_component_installer.cc b/chrome/browser/component_updater/recovery_component_installer.cc
index 696ab4328c295a07084999cc5bd4b75e46d7e089..20898059d1394103ac2c6bdfed1deed3f4059fdb 100644
--- a/chrome/browser/component_updater/recovery_component_installer.cc
+++ b/chrome/browser/component_updater/recovery_component_installer.cc
@@ -186,6 +186,8 @@ class RecoveryComponentInstaller : public update_client::ComponentInstaller {
   bool GetInstalledFile(const std::string& file,
                         base::FilePath* installed_file) override;
 
+  bool Uninstall() override;
+
  private:
   ~RecoveryComponentInstaller() override {}
 
@@ -360,6 +362,10 @@ bool RecoveryComponentInstaller::GetInstalledFile(
   return false;
 }
 
+bool RecoveryComponentInstaller::Uninstall() {
+  return false;
+}
+
 void RegisterRecoveryComponent(ComponentUpdateService* cus,
                                PrefService* prefs) {
 #if !defined(OS_CHROMEOS)