Replace ExtensionInstallChecker with generic PreloadCheckGroup

extensions/browser/preload_check_group.h

Index: extensions/browser/preload_check_group.h
diff --git a/extensions/browser/preload_check_group.h b/extensions/browser/preload_check_group.h
new file mode 100644
index 0000000000000000000000000000000000000000..574f78b8d9ffb5eb47b369c7987378aab208ccaa
--- /dev/null
+++ b/extensions/browser/preload_check_group.h
@@ -0,0 +1,60 @@
+// 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_GROUP_H_
+#define EXTENSIONS_BROWSER_PRELOAD_CHECK_GROUP_H_
+
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/threading/thread_checker.h"
+#include "extensions/browser/preload_check.h"
+
+namespace extensions {
+
+// PreloadCheckGroup runs a collection of other PreloadChecks and reports their
+// collective status once they have all finished. To stop the remaining checks
+// upon hitting the first error, use set_stop_on_first_error().
+class PreloadCheckGroup : public PreloadCheck {
+ public:
+  PreloadCheckGroup();
+  ~PreloadCheckGroup() override;
+
+  // Adds a check to run. Not owned. Must be called before Start().
+  void AddCheck(PreloadCheck* check);
+
+  // PreloadCheck:
+  void Start(ResultCallback callback) override;
+
+  void set_stop_on_first_error(bool value) { stop_on_first_error_ = value; }
+
+ private:
+  // Saves any errors and may invoke the callback.
+  virtual void OnCheckComplete(Errors errors);
+
+  // Invokes the callback if the checks are considered finished.
+  void MaybeInvokeCallback();
+
+  base::ThreadChecker thread_checker_;
+
+  // If true, the callback is invoked early when the first check fails,
+  // stopping the remaining checks.
+  bool stop_on_first_error_ = false;
+
+  // Checks to run. Not owned.
+  std::vector<PreloadCheck*> checks_;
+
+  ResultCallback callback_;
+  int running_checks_ = 0;
+  Errors errors_;
+
+  base::WeakPtrFactory<PreloadCheckGroup> weak_ptr_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(PreloadCheckGroup);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_BROWSER_PRELOAD_CHECK_GROUP_H_