Extract ResultCatcher from ExtensionApiTest. Use it in ShellApiTest.

extensions/test/result_catcher.h

+// Copyright 2014 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_TEST_RESULT_CATCHER_H_
+#define EXTENSIONS_TEST_RESULT_CATCHER_H_
+
+#include <deque>
+#include <string>
+
+#include "base/compiler_specific.h"
+#include "content/public/browser/notification_observer.h"
+#include "content/public/browser/notification_registrar.h"
+
+namespace content {
+class BrowserContext;
+}  // namespace content
+
+namespace extensions {
+
+// Helper class that observes tests failing or passing. Observation starts

[James Cook, 2014/09/03 18:08:42]

What's the plan for ExtensionApiTest::ResultCatcher?

[Yoyo Zhou, 2014/09/04 21:57:42]

It will be replaced with this one. Added a TODO.

+// when the class is constructed. Get the next result by calling
+// GetNextResult() and message() if GetNextResult() return false. If there
+// are no results, this method will pump the UI message loop until one is
+// received.
+class ResultCatcher : public content::NotificationObserver {
+ public:
+  ResultCatcher();
+  virtual ~ResultCatcher();
+
+  // Pumps the UI loop until a notification is received that an API test
+  // succeeded or failed. Returns true if the test succeeded, false otherwise.
+  bool GetNextResult();
+
+  void RestrictToBrowserContext(content::BrowserContext* context) {
+    context_restriction_ = context;
+  }
+
+  const std::string& message() { return message_; }
+
+ private:
+  virtual void Observe(int type,

[James Cook, 2014/09/03 18:08:42]

Comment about which interface you are overriding

[Yoyo Zhou, 2014/09/04 21:57:42]

Done.

+                       const content::NotificationSource& source,
+                       const content::NotificationDetails& details) OVERRIDE;
+
+  content::NotificationRegistrar registrar_;
+
+  // A sequential list of pass/fail notifications from the test extension(s).
+  std::deque<bool> results_;
+
+  // If it failed, what was the error message?
+  std::deque<std::string> messages_;
+  std::string message_;
+
+  // If non-NULL, we will listen to events from this BrowserContext only.
+  content::BrowserContext* context_restriction_;

[James Cook, 2014/09/03 18:08:42]

it's horribly long but I would call this browser_context_restriction_

[Yoyo Zhou, 2014/09/04 21:57:42]

Done.

+
+  // True if we're in a nested message loop waiting for results from
+  // the extension.
+  bool waiting_;
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_TEST_RESULT_CATCHER_H_