Update ExtensionInstallChecker to use PreloadCheck classes

extensions/browser/preload_check_test_util.h

Index: extensions/browser/preload_check_test_util.h
diff --git a/extensions/browser/preload_check_test_util.h b/extensions/browser/preload_check_test_util.h
index 7da768af493ab4e0dccc8d0457ed6db558f801a8..d96a514ba77600553195746fa776e579d153c5bd 100644
--- a/extensions/browser/preload_check_test_util.h
+++ b/extensions/browser/preload_check_test_util.h
@@ -7,6 +7,9 @@
 
 #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 {
@@ -51,6 +54,31 @@ class PreloadCheckRunner {
   DISALLOW_COPY_AND_ASSIGN(PreloadCheckRunner);
 };
 
+// Stub for a PreloadCheck that returns the desired error(s).
+class PreloadCheckStub : public PreloadCheck {
+ public:
+  explicit PreloadCheckStub(bool is_async = false);

[Devlin, 2017/03/22 15:08:46]

Maybe an enum, SYNCHRONOUS and ASYNCHRONOUS?  Makes the call sites much more
readable.

[michaelpg, 2017/03/24 02:34:17]

I'll add set_is_async to mirror ExtensionInstallCheckerForTest. That may come in
handy soon....

+  ~PreloadCheckStub() override;
+
+  void AddError(Error error);
+  void set_error_message(const base::string16& message) { message_ = message; }
+
+  // PreloadCheck:
+  void Start(ResultCallback callback) override;
+  base::string16 GetErrorMessage() const override;
+
+ private:
+  void StartInternal(ResultCallback callback);
+
+  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_