Using ShellObserver instead of creating MaximizeModeController::Observer

ash/system/chromeos/power/tablet_power_button_controller_unittest.cc

Index: ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
diff --git a/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc b/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
index 812c9993ddde6b569142070399dbdf6f2f8ea11f..d33290733fa35171db3639fd6f09f96af7c30588 100644
--- a/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
+++ b/ash/system/chromeos/power/tablet_power_button_controller_unittest.cc
@@ -415,7 +415,7 @@ TEST_F(TabletPowerButtonControllerTest,
 
   power_manager_client_->SendPowerButtonEvent(true, tick_clock_->NowTicks());
   EXPECT_TRUE(test_api_->ShutdownTimerIsRunning());
-  tablet_controller_->OnEnterMaximizeMode();
+  tablet_controller_->OnMaximizeModeStarted();
   EXPECT_FALSE(test_api_->ShutdownTimerIsRunning());
   tick_clock_->Advance(base::TimeDelta::FromMilliseconds(1500));
   power_manager_client_->SendPowerButtonEvent(false, tick_clock_->NowTicks());
@@ -425,7 +425,7 @@ TEST_F(TabletPowerButtonControllerTest,
   power_manager_client_->SendPowerButtonEvent(true, tick_clock_->NowTicks());
   test_api_->TriggerShutdownTimeout();
   EXPECT_TRUE(lock_state_test_api_->shutdown_timer_is_running());
-  tablet_controller_->OnEnterMaximizeMode();
+  tablet_controller_->OnMaximizeModeStarted();
   EXPECT_FALSE(lock_state_test_api_->shutdown_timer_is_running());
   tick_clock_->Advance(base::TimeDelta::FromMilliseconds(2500));
   power_manager_client_->SendPowerButtonEvent(false, tick_clock_->NowTicks());
@@ -434,7 +434,7 @@ TEST_F(TabletPowerButtonControllerTest,
 
   power_manager_client_->SendPowerButtonEvent(true, tick_clock_->NowTicks());
   EXPECT_TRUE(test_api_->ShutdownTimerIsRunning());
-  tablet_controller_->OnLeaveMaximizeMode();
+  tablet_controller_->OnMaximizeModeEnded();
   EXPECT_FALSE(test_api_->ShutdownTimerIsRunning());
   tick_clock_->Advance(base::TimeDelta::FromMilliseconds(3500));
   power_manager_client_->SendPowerButtonEvent(false, tick_clock_->NowTicks());
@@ -444,7 +444,7 @@ TEST_F(TabletPowerButtonControllerTest,
   power_manager_client_->SendPowerButtonEvent(true, tick_clock_->NowTicks());
   test_api_->TriggerShutdownTimeout();
   EXPECT_TRUE(lock_state_test_api_->shutdown_timer_is_running());
-  tablet_controller_->OnLeaveMaximizeMode();
+  tablet_controller_->OnMaximizeModeEnded();
   EXPECT_FALSE(lock_state_test_api_->shutdown_timer_is_running());
   tick_clock_->Advance(base::TimeDelta::FromMilliseconds(4500));
   power_manager_client_->SendPowerButtonEvent(false, tick_clock_->NowTicks());