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/updater_state_unittest.cc b/components/update_client/updater_state_unittest.cc
index ea724b077..d8d96b3 100644
--- a/components/update_client/updater_state_unittest.cc
+++ b/components/update_client/updater_state_unittest.cc
@@ -15,8 +15,8 @@
 
 class UpdaterStateTest : public testing::Test {
  public:
-  UpdaterStateTest() {}
-  ~UpdaterStateTest() override {}
+  UpdaterStateTest() = default;
+  ~UpdaterStateTest() override = default;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(UpdaterStateTest);