Replace ExtensionInstallChecker with generic PreloadCheckGroup

extensions/browser/requirements_checker_unittest.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/requirements_checker.h"
 
 #include <memory>
 #include <vector>
 
 #include "base/memory/ptr_util.h"
@@ skipping 147 matching lines @@
 
 // Tests a requirement that might fail asynchronously.
 TEST_F(RequirementsCheckerTest, RequirementsFailWebGL) {
   content::GpuDataManager::GetInstance()->BlacklistWebGLForTesting();
   RequireFeature(kFeatureWebGL);
   CreateExtension();
   StartChecker();
 
   // TODO(michaelpg): Check that the runner actually finishes, which requires
   // waiting for the GPU check to succeed: crbug.com/706204.
-  runner_.WaitForIdle();
   if (runner_.errors().size()) {
     EXPECT_THAT(runner_.errors(), testing::UnorderedElementsAre(
                                       PreloadCheck::WEBGL_NOT_SUPPORTED));
     EXPECT_FALSE(checker_->GetErrorMessage().empty());
   }
 }
 
 }  // namespace extensions