Chrome Cleaner UI: Use BrowserThread's DeleteOnIOThread for ChromePromptImpl

chrome/browser/safe_browsing/chrome_cleaner/srt_chrome_prompt_impl.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/safe_browsing/chrome_cleaner/srt_chrome_prompt_impl.h"
 
 #include <utility>
 
 #include "base/location.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "content/public/browser/browser_thread.h"
 
+using content::BrowserThread;
+
 namespace safe_browsing {
 
 using chrome_cleaner::mojom::ChromePrompt;
 using chrome_cleaner::mojom::ChromePromptRequest;
 using chrome_cleaner::mojom::ElevationStatus;
 using chrome_cleaner::mojom::PromptAcceptance;
 using chrome_cleaner::mojom::UwSPtr;
 
 ChromePromptImpl::ChromePromptImpl(ChromePromptRequest request,
                                    base::Closure on_connection_closed,
                                    OnPromptUser on_prompt_user)
     : binding_(this, std::move(request)),
       on_prompt_user_(std::move(on_prompt_user)) {
   DCHECK(on_prompt_user_);
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
   binding_.set_connection_error_handler(std::move(on_connection_closed));
 }
 
-ChromePromptImpl::~ChromePromptImpl() {}
+ChromePromptImpl::~ChromePromptImpl() {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+}
 
 void ChromePromptImpl::PromptUser(std::vector<UwSPtr> removable_uws_found,
                                   ElevationStatus elevation_status,
                                   ChromePrompt::PromptUserCallback callback) {
   auto files_to_delete = base::MakeUnique<std::set<base::FilePath>>();
   for (const UwSPtr& uws_ptr : removable_uws_found) {
     files_to_delete->insert(uws_ptr->files_to_delete.begin(),
                             uws_ptr->files_to_delete.end());
   }
 
   if (on_prompt_user_) {
     std::move(on_prompt_user_)
         .Run(std::move(files_to_delete), std::move(callback));
   }
 }
 
 }  // namespace safe_browsing