Replace ExtensionInstallChecker with generic PreloadCheckGroup

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 3ef1fd99de47f1f895b8304a5689e819924c6475..c2e512733b87cfc509292228599d1d34c00cea41 100644
--- a/extensions/browser/preload_check_test_util.h
+++ b/extensions/browser/preload_check_test_util.h
@@ -30,13 +30,13 @@ class PreloadCheckRunner {
   // Starts the check and waits for its callback to execute.
   void RunUntilComplete(PreloadCheck* check);
 
-  // Runs the message loop until OnCheckComplete is called.
-  void WaitForCompletion();
-
   // Runs the message loop until idle. Useful to see whether OnCheckComplete is
   // called without waiting indefinitely.
   void WaitForIdle();
 
+  // Runs the message loop until OnCheckComplete is called.
+  void WaitForComplete();
+
   PreloadCheck::ResultCallback GetCallback();
 
   const PreloadCheck::Errors& errors() const { return errors_; }
@@ -54,28 +54,24 @@ class PreloadCheckRunner {
   DISALLOW_COPY_AND_ASSIGN(PreloadCheckRunner);
 };
 
-// Stub for a PreloadCheck that returns the desired error(s).
+// Stub for a PreloadCheck that calls the callback with the given error(s).
 class PreloadCheckStub : public PreloadCheck {
  public:
-  PreloadCheckStub();
+  explicit PreloadCheckStub(const Errors& errors = Errors());

[Devlin, 2017/04/06 02:03:53]

nit: I'd prefer we don't use default arguments on non-POD data.  Let's keep
either a SetErrors() method, or pass in an empty array in cases of no error.

[michaelpg, 2017/04/06 22:31:16]

Done.

   ~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; }
+  bool started() const { return started_; }
 
   // PreloadCheck:
   void Start(ResultCallback callback) override;
-  base::string16 GetErrorMessage() const override;
 
  private:
   void RunCallback(ResultCallback callback);
 
   bool is_async_ = false;
+  bool started_ = false;
   Errors errors_;
-  base::string16 message_;
 
   base::WeakPtrFactory<PreloadCheckStub> weak_ptr_factory_;