Use `default` instead of empty body ctor and dtor definitions.

This is a mechanical change over files in the update_client,
component_updater, and the extension updater.

Change-Id: I2a5b682299cbb04bdfa9f5691329dfa97e869d2c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2104396
Reviewed-by: Joshua Pawlicki <[email protected]>
Commit-Queue: Sorin Jianu <[email protected]>
Cr-Commit-Position: refs/heads/master@{#750544}
diff --git a/components/update_client/crx_downloader_unittest.cc b/components/update_client/crx_downloader_unittest.cc
index 6ec80fb..865c968 100644
--- a/components/update_client/crx_downloader_unittest.cc
+++ b/components/update_client/crx_downloader_unittest.cc
@@ -115,7 +115,7 @@
           base::MakeRefCounted<network::WeakWrapperSharedURLLoaderFactory>(
               &test_url_loader_factory_)) {}
 
-CrxDownloaderTest::~CrxDownloaderTest() {}
+CrxDownloaderTest::~CrxDownloaderTest() = default;
 
 void CrxDownloaderTest::SetUp() {
   num_download_complete_calls_ = 0;