Unconditionally delete the unpack path in the UpdateClient.

components/update_client/test_installer.h

Index: components/update_client/test_installer.h
diff --git a/components/update_client/test_installer.h b/components/update_client/test_installer.h
index 1b5bea0bda11710b37f46b57ac2a07d74cd3a6ae..473772e8a0f5273de1e4e2ab47ae0581c879603e 100644
--- a/components/update_client/test_installer.h
+++ b/components/update_client/test_installer.h
@@ -42,6 +42,10 @@ class TestInstaller : public CrxInstaller {
 
   int error_;
   int install_count_;
+
+ private:
+  // Contains the |unpack_path| argument of the Install call.
+  base::FilePath unpack_path_;
 };
 
 // A ReadOnlyTestInstaller is an installer that knows about files in an existing