Add support for uninstalling components and use it in SupervisedUserWhitelistInstaller.

chrome/browser/component_updater/swiftshader_component_installer.cc

Index: chrome/browser/component_updater/swiftshader_component_installer.cc
diff --git a/chrome/browser/component_updater/swiftshader_component_installer.cc b/chrome/browser/component_updater/swiftshader_component_installer.cc
index 917a3ca4c86e8d054c08de148169124678716168..f0a59f1ca442e432fe4cbe5f12711669e1a68536 100644
--- a/chrome/browser/component_updater/swiftshader_component_installer.cc
+++ b/chrome/browser/component_updater/swiftshader_component_installer.cc
@@ -109,6 +109,8 @@ class SwiftShaderComponentInstaller : public update_client::ComponentInstaller {
   bool GetInstalledFile(const std::string& file,
                         base::FilePath* installed_file) override;
 
+  bool Uninstall() override;
+
  private:
   ~SwiftShaderComponentInstaller() override {}
 
@@ -163,6 +165,10 @@ bool SwiftShaderComponentInstaller::GetInstalledFile(
   return false;
 }
 
+bool SwiftShaderComponentInstaller::Uninstall() {
+  return false;
+}
+
 void FinishSwiftShaderUpdateRegistration(ComponentUpdateService* cus,
                                          const Version& version) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));