Fix -Winconsistent-missing-override in CrashReportUploadThread

handler/crash_report_upload_thread.cc

 // Copyright 2015 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 127 matching lines @@
 }  // namespace
 
 namespace internal {
 
 class CrashReportUploadHelperThread final : public Thread {
  public:
   explicit CrashReportUploadHelperThread(CrashReportUploadThread* self)
       : self_(self) {}
   ~CrashReportUploadHelperThread() override {}
 
-  virtual void ThreadMain() {
+  void ThreadMain() override {
     self_->ThreadMain();
   }
 
  private:
   CrashReportUploadThread* self_;
 
   DISALLOW_COPY_AND_ASSIGN(CrashReportUploadHelperThread);
 };
 
 }  // namespace internal
@@ skipping 212 matching lines @@
   http_transport->SetTimeout(60.0);  // 1 minute.
 
   if (!http_transport->ExecuteSynchronously(response_body)) {
     return UploadResult::kRetry;
   }
 
   return UploadResult::kSuccess;
 }
 
 }  // namespace crashpad