Use PreloadCheckGroup in ExtensionInstallChecker. Make RequirementsChecker a PreloadCheck.

extensions/browser/preload_check_group.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 "extensions/browser/preload_check_group.h"
 
 #include "content/public/browser/browser_thread.h"
 
 namespace extensions {
 
@@ skipping 14 matching lines @@
 
 void PreloadCheckGroup::Start(ResultCallback callback) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DCHECK(running_checks_ == 0);
   DCHECK(!callback.is_null());
 
   callback_ = std::move(callback);
 
   running_checks_ = checks_.size();
   for (auto* check : checks_) {
-    check->Start(base::Bind(&PreloadCheckGroup::OnCheckComplete,
-                            weak_ptr_factory_.GetWeakPtr(), check,
-                            current_sequence_number_));
+    check->Start(base::BindOnce(&PreloadCheckGroup::OnCheckComplete,
+                                weak_ptr_factory_.GetWeakPtr(), check,
+                                current_sequence_number_));
     // Synchronous checks may fail immediately.
     if (running_checks_ == 0)
       return;
   }
 }
 
 /*
 base::string16 PreloadCheckGroup::GetErrorMessage() const {
   DCHECK_NE(error, nullptr);
   if (error_.empty())
@@ skipping 33 matching lines @@
     running_checks_ = 0;
     ++current_sequence_number_;
 
     std::move(callback_).Run(errors_);
     CHECK(callback_.is_null());
     CHECK(!callback_);
   }
 }
 
 }  // namespace extensions