Fix drive-by presubmit warnings

Presubmit warnings found as part of touching many files in
https://chromium-review.googlesource.com/c/chromium/src/+/1756247

R=hansberry@chromium.org, msw@chromium.org

Bug: 992483
Change-Id: I76ceb6ded41b61a27ea0fd0b0cd7d7ee7d66596f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1757507
Auto-Submit: Gabriel Charette <gab@chromium.org>
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Michael Wasserman <msw@chromium.org>
Commit-Queue: Gabriel Charette <gab@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688207}

chrome/browser/ui/views/frame/web_contents_close_handler_unittest.cc

@@ -12,7 +12,7 @@
 class MockWebContentsCloseHandlerDelegate
     : public WebContentsCloseHandlerDelegate {
  public:
-  explicit MockWebContentsCloseHandlerDelegate()
+  MockWebContentsCloseHandlerDelegate()
       : task_environment_(base::test::TaskEnvironment::MainThreadType::UI),
         got_clone_(false),
         got_destroy_(false) {}

chromeos/services/secure_channel/active_connection_manager_impl_unittest.cc

@@ -28,7 +28,8 @@ namespace {
 
 class FakeMultiplexedChannelFactory : public MultiplexedChannelImpl::Factory {
  public:
-  FakeMultiplexedChannelFactory(MultiplexedChannel::Delegate* expected_delegate)
+  explicit FakeMultiplexedChannelFactory(
+      MultiplexedChannel::Delegate* expected_delegate)
       : expected_delegate_(expected_delegate) {}
   ~FakeMultiplexedChannelFactory() override = default;
 

chromeos/services/secure_channel/connection_attempt_base_unittest.cc

@@ -40,7 +40,7 @@ const char kTestLocalDeviceId[] = "testLocalDeviceId";
 class TestConnectionAttempt
     : public ConnectionAttemptBase<BleInitiatorFailureType> {
  public:
-  TestConnectionAttempt(FakeConnectionAttemptDelegate* delegate)
+  explicit TestConnectionAttempt(FakeConnectionAttemptDelegate* delegate)
       : ConnectionAttemptBase<BleInitiatorFailureType>(
             delegate,
             ConnectionAttemptDetails(kTestRemoteDeviceId,