Introduce web::TestWebThreadBundle

ios/web/public/test/test_web_thread_bundle.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 IOS_WEB_PUBLIC_TEST_TEST_WEB_THREAD_BUNDLE_H_
+#define IOS_WEB_PUBLIC_TEST_TEST_WEB_THREAD_BUNDLE_H_
+
+// TestWebThreadBundle is a convenience class for creating a set of
+// TestWebThreads in unit tests.  For most tests, it is sufficient to
+// just instantiate the TestWebThreadBundle as a member variable.
+//
+// By default, all of the created TestWebThreads will be backed by a single
+// shared MessageLoop. If a test truly needs separate threads, it can do
+// so by passing the appropriate combination of RealThreadsMask values during
+// the TestWebThreadBundle construction.
+//
+// The TestWebThreadBundle will attempt to drain the MessageLoop on
+// destruction. Sometimes a test needs to drain currently enqueued tasks
+// mid-test.
+//
+// The TestWebThreadBundle will also flush the blocking pool on destruction.
+// We do this to avoid memory leaks, particularly in the case of threads posting
+// tasks to the blocking pool via PostTaskAndReply. By ensuring that the tasks
+// are run while the originating TestBroswserThreads still exist, we prevent
+// leakage of PostTaskAndReplyRelay objects. We also flush the blocking pool
+// again at the point where it would normally be shut down, to better simulate
+// the normal thread shutdown process.
+//
+// Some tests using the IO thread expect a MessageLoopForIO. Passing
+// IO_MAINLOOP will use a MessageLoopForIO for the main MessageLoop.
+// Most of the time, this avoids needing to use a REAL_IO_THREAD.
+
+#include "base/memory/scoped_ptr.h"
+
+namespace web {
+
+class TestWebThreadBundleImpl;
+
+class TestWebThreadBundle {
+ public:
+  // Used to specify the type of MessageLoop that backs the UI thread, and
+  // which of the named WebThreads should be backed by a real
+  // threads. The UI thread is always the main thread in a unit test.
+  enum Options {
+    DEFAULT = 0x00,
+    IO_MAINLOOP = 0x01,
+    REAL_DB_THREAD = 0x02,
+    REAL_FILE_THREAD = 0x08,
+    REAL_FILE_USER_BLOCKING_THREAD = 0x10,
+    REAL_CACHE_THREAD = 0x20,
+    REAL_IO_THREAD = 0x40,
+  };
+
+  TestWebThreadBundle();
+  explicit TestWebThreadBundle(int options);
+
+  ~TestWebThreadBundle();
+
+ private:
+  scoped_ptr<TestWebThreadBundleImpl> impl_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestWebThreadBundle);
+};
+
+}  // namespace web
+
+#endif  // IOS_WEB_PUBLIC_TEST_TEST_WEB_THREAD_BUNDLE_H_