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 109 matching lines @@
       have_seen_accelerometer_data_(false),
       ignore_display_configuration_updates_(false),
       lid_open_past_180_(false),
       shutting_down_(false),
       user_rotation_(gfx::Display::ROTATE_0),
       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
 }
 
 void MaximizeModeController::SetRotationLocked(bool rotation_locked) {
   if (rotation_locked_ == rotation_locked)
     return;
   base::AutoReset<bool> auto_ignore_display_configuration_updates(
       &ignore_display_configuration_updates_, true);
@@ skipping 358 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