Add BackgroundModeOptimizer that can restart the browser

chrome/browser/background/background_mode_optimizer_unittest.cc

+// Copyright 2016 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.
+
+#include <memory>
+
+#include "chrome/browser/background/background_mode_optimizer.h"
+#include "chrome/browser/browser_shutdown.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+// Dummy optimizer that skips doing the restart.
+// friend with BackgroundModeOptimizer, can't be in the anonymous namespace.
+class DummyBackgroundModeOptimizer : public BackgroundModeOptimizer {
+ public:
+  DummyBackgroundModeOptimizer() {}
+  MOCK_METHOD0(DoRestart, void());
+};
+
+TEST(BackgroundModeOptimizerTest, Foo) {
+  // Strict mock, will fail the test if a non expected call is made.
+  testing::StrictMock<DummyBackgroundModeOptimizer> optimizer;
+
+  // No restart until we have at least one browser that got opened
+  optimizer.OnKeepAliveRestartStateChanged(true);
+
+  optimizer.OnBrowserAdded(nullptr);
+  EXPECT_CALL(optimizer, DoRestart()).RetiresOnSaturation();
+  optimizer.OnKeepAliveRestartStateChanged(true);
+
+  // Restart should not be called when we are trying to quit
+  browser_shutdown::SetTryingToQuit(true);
+  optimizer.OnKeepAliveRestartStateChanged(true);
+
+  // Restart should check that restart changed to be allowed.
+  browser_shutdown::SetTryingToQuit(false);
+  optimizer.OnKeepAliveRestartStateChanged(false);
+
+  EXPECT_CALL(optimizer, DoRestart()).RetiresOnSaturation();
+  optimizer.OnKeepAliveRestartStateChanged(true);
+}