Add TestBrowserThreadBundle into RenderViewHostTestHarness. Kill some unnecessary real threads.

content/public/test/test_browser_thread_bundle.h

Index: content/public/test/test_browser_thread_bundle.h
diff --git a/content/public/test/test_browser_thread_bundle.h b/content/public/test/test_browser_thread_bundle.h
new file mode 100644
index 0000000000000000000000000000000000000000..31927fe2e3d478857138289cd237452a9c79e205
--- /dev/null
+++ b/content/public/test/test_browser_thread_bundle.h
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+// Copyright (c) 2013 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.
+
+// TestBrowserThreadBundle is a convenience class for creating a set of
+// TestBrowserThreads in unit tests.  For most tests, it is sufficient to
+// just instantiate the TestBrowserThreadBundle as a member variable.
+//
+// By default, each of the created TestBrowserThreads will be backed by
+// all of the created TestBrowserThreads will be backed by a single
+// shared MessageLoop. If a test truly needs separate threads, it can do
+// so by passing the apprpriate combination of RealThreadsMask values during
+// the TestBrowserThreadBundle construction.
+//
+// The TestBrowserThreadBundle will attempt to drain the MessageLoop on
+// destruction. If a test needs to drain currently enqueued tasks, the best
+// pattern is to instantiate base::RunLoop and call the appropriate methods
+// the RunLoop (eg., base::RunLoop().RunUntilIdle()). Very rarely should a
+// test talk directly to the underlying MessageLoop.
+//
+// Some tests using the IO thread expect a MessageLoopForIO. Currently, the
+// best workaround is to create a REAL_IO_THREAD to get the appropriate mesasge
+// loop. This class could conceivably create a MessageLoopForIO instead of
+// a MessageLoopForUI as the main loop, but there are not enough cases to
+// make it work the API complexity.
+
+#ifndef BROWSER_THREAD_TEST_BUNDLE_H_
+#define BROWSER_THREAD_TEST_BUNDLE_H_
+
+#include "base/message_loop.h"
+#include "content/public/test/test_browser_thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+class TestBrowserThreadBundle {
+ public:
+  // Used to specifying which named BrowserThreads should be backed by a real
+  // thread rather than main main thread.  The UI thread is always the main
+  // thread in a unit test so it is left out of this enum.
+  enum RealThreadsMask {
+    NO_REAL_THREAD = 0x0,
+    REAL_DB_THREAD = 0x01,
+    REAL_FILE_THREAD = 0x2,
+    REAL_FILE_USER_BLOCKING_THREAD = 0x4,
+    REAL_IO_THREAD = 0x8
+  };
+
+  TestBrowserThreadBundle();
+  explicit TestBrowserThreadBundle(int real_threads_mask);
+
+  ~TestBrowserThreadBundle();
+
+  TestBrowserThread* ui_thread() { return &ui_thread_; }
+  TestBrowserThread* db_thread() { return &db_thread_; }
+  TestBrowserThread* file_thread() { return &file_thread_; }
+  TestBrowserThread* file_user_blocking_thread() {
+    return &file_user_blocking_thread_;
+  }
+  TestBrowserThread* io_thread() { return &io_thread_; }
+
+ private:
+  MessageLoopForUI message_loop_;
+  TestBrowserThread ui_thread_;
+  TestBrowserThread db_thread_;
+  TestBrowserThread file_thread_;
+  TestBrowserThread file_user_blocking_thread_;
+  TestBrowserThread io_thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestBrowserThreadBundle);
+};
+
+}  // namespace content
+
+#endif /* BROWSER_THREAD_TEST_BUNDLE_H_ */