Change AccelerometerReader to a Singleton

ash/wm/maximize_mode/maximize_mode_controller.cc

 // 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.
 
 #include "ash/wm/maximize_mode/maximize_mode_controller.h"
 
 #include "ash/accelerators/accelerator_controller.h"
 #include "ash/accelerators/accelerator_table.h"
 #include "ash/ash_switches.h"
 #include "ash/display/display_manager.h"
@@ skipping 61 matching lines @@
 }  // namespace
 
 MaximizeModeController::MaximizeModeController()
     : have_seen_accelerometer_data_(false),
       lid_open_past_180_(false),
       last_touchview_transition_time_(base::Time::Now()),
       tick_clock_(new base::DefaultTickClock()),
       lid_is_closed_(false) {
   Shell::GetInstance()->AddShellObserver(this);
 #if defined(OS_CHROMEOS)
-  Shell::GetInstance()->accelerometer_reader()->AddObserver(this);
+  chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
   chromeos::DBusThreadManager::Get()->
       GetPowerManagerClient()->AddObserver(this);
 #endif  // OS_CHROMEOS
 }
 
 MaximizeModeController::~MaximizeModeController() {
   Shell::GetInstance()->RemoveShellObserver(this);
 #if defined(OS_CHROMEOS)
-  Shell::GetInstance()->accelerometer_reader()->RemoveObserver(this);
+  chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
   chromeos::DBusThreadManager::Get()->
       GetPowerManagerClient()->RemoveObserver(this);
 #endif  // OS_CHROMEOS
 }
 
 bool MaximizeModeController::CanEnterMaximizeMode() {
   // If we have ever seen accelerometer data, then HandleHingeRotation may
   // trigger maximize mode at some point in the future.
   // The --enable-touch-view-testing switch can also mean that we may enter
   // maximize mode.
@@ skipping 194 matching lines @@
   return elapsed_time <= kLidRecentlyOpenedDuration;
 }
 
 void MaximizeModeController::SetTickClockForTest(
     scoped_ptr<base::TickClock> tick_clock) {
   DCHECK(tick_clock_);
   tick_clock_ = tick_clock.Pass();
 }
 
 }  // namespace ash