Update ExtensionInstallChecker to use PreloadCheck classes

extensions/browser/preload_check_test_util.h

 // 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.
 
 #ifndef EXTENSIONS_BROWSER_PRELOAD_CHECK_TEST_UTIL_H_
 #define EXTENSIONS_BROWSER_PRELOAD_CHECK_TEST_UTIL_H_
 
 #include <memory>
 
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/strings/string16.h"
 #include "extensions/browser/preload_check.h"
 
 namespace base {
 class RunLoop;
 }
 
 namespace extensions {
 
 // Provides a callback method for a PreloadCheck that stores its results.
 class PreloadCheckRunner {
@@ skipping 24 matching lines @@
 
   PreloadCheck::Errors errors_;
   bool called_;
 
   // Using a RunLoop data member would trigger tricky timing troubles.
   std::unique_ptr<base::RunLoop> run_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(PreloadCheckRunner);
 };
 
+// Stub for a PreloadCheck that returns the desired error(s).
+class PreloadCheckStub : public PreloadCheck {
+ public:
+  PreloadCheckStub();
+  ~PreloadCheckStub() override;
+
+  void AddError(Error error);
+  void set_error_message(const base::string16& message) { message_ = message; }
+
+  bool is_async() const { return is_async_; }
+  void set_is_async(bool is_async) { is_async_ = is_async; }
+
+  // PreloadCheck:
+  void Start(ResultCallback callback) override;
+  base::string16 GetErrorMessage() const override;
+
+ private:
+  void RunCallback(ResultCallback callback);
+
+  // Defaults to false.

[Devlin, 2017/03/24 16:21:48]

optional: if you use c++11 fanciness and inline the defaults, this comment is
unnecessary :)

bool is_async_ = false;

[michaelpg, 2017/03/24 21:48:28]

Cool! Done in a couple other places.

+  bool is_async_;
+  Errors errors_;
+  base::string16 message_;
+
+  base::WeakPtrFactory<PreloadCheckStub> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreloadCheckStub);
+};
+
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_PRELOAD_CHECK_TEST_UTIL_H_