Change AccelerometerReader to a Singleton

On ChromeOS the accelerometer needs to be read by both ash/ and content/

This change removes the ownership of AccelerometerReader from Shell, changing it into a Singleton.

TEST=Confirmed that a device with an accelerometer enters maximize mode.
BUG=342908

Review URL: https://codereview.chromium.org/822503003

Cr-Commit-Position: refs/heads/master@{#311353}

ash/content/display/screen_orientation_controller_chromeos.cc

@@ -74,7 +74,7 @@ ScreenOrientationController::ScreenOrientationController()
 ScreenOrientationController::~ScreenOrientationController() {
   content::ScreenOrientationProvider::SetDelegate(NULL);
   Shell::GetInstance()->RemoveShellObserver(this);
-  Shell::GetInstance()->accelerometer_reader()->RemoveObserver(this);
+  chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
   Shell::GetInstance()->display_controller()->RemoveObserver(this);
 }
 
@@ -220,14 +220,14 @@ void ScreenOrientationController::OnMaximizeModeStarted() {
       display_manager->GetDisplayInfo(gfx::Display::InternalDisplayId())
           .rotation();
   LoadDisplayRotationProperties();
-  Shell::GetInstance()->accelerometer_reader()->AddObserver(this);
+  chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
   Shell::GetInstance()->display_controller()->AddObserver(this);
 }
 
 void ScreenOrientationController::OnMaximizeModeEnded() {
   if (!Shell::GetInstance()->display_manager()->HasInternalDisplay())
     return;
-  Shell::GetInstance()->accelerometer_reader()->RemoveObserver(this);
+  chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
   Shell::GetInstance()->display_controller()->RemoveObserver(this);
   if (current_rotation_ != user_rotation_)
     SetDisplayRotation(user_rotation_);

ash/shell.cc

@@ -138,7 +138,6 @@
 #include "ash/virtual_keyboard_controller.h"
 #include "base/bind_helpers.h"
 #include "base/sys_info.h"
-#include "chromeos/accelerometer/accelerometer_reader.h"
 #include "chromeos/dbus/dbus_thread_manager.h"
 #include "ui/chromeos/user_activity_power_manager_notifier.h"
 #include "ui/display/chromeos/display_configurator.h"
@@ -638,7 +637,6 @@ Shell::Shell(ShellDelegate* delegate)
       window_positioner_(new WindowPositioner),
       activation_client_(NULL),
 #if defined(OS_CHROMEOS)
-      accelerometer_reader_(new chromeos::AccelerometerReader()),
       display_configurator_(new ui::DisplayConfigurator()),
 #endif  // defined(OS_CHROMEOS)
       native_cursor_manager_(new AshNativeCursorManager),

ash/shell.h

@@ -42,12 +42,6 @@ class FocusClient;
 }
 }
 
-#if defined(OS_CHROMEOS)
-namespace chromeos {
-class AccelerometerReader;
-}
-#endif
-
 namespace gfx {
 class ImageSkia;
 class Point;
@@ -517,10 +511,6 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   }
 
 #if defined(OS_CHROMEOS)
-  chromeos::AccelerometerReader* accelerometer_reader() {
-    return accelerometer_reader_.get();
-  }
-
   // TODO(oshima): Move these objects to DisplayController.
   ui::DisplayConfigurator* display_configurator() {
     return display_configurator_.get();
@@ -714,7 +704,6 @@ class ASH_EXPORT Shell : public SystemModalContainerEventFilterDelegate,
   scoped_ptr<LocaleNotificationController> locale_notification_controller_;
 
 #if defined(OS_CHROMEOS)
-  scoped_ptr<chromeos::AccelerometerReader> accelerometer_reader_;
   scoped_ptr<PowerEventObserver> power_event_observer_;
   scoped_ptr<ui::UserActivityPowerManagerNotifier> user_activity_notifier_;
   scoped_ptr<VideoActivityNotifier> video_activity_notifier_;

ash/wm/maximize_mode/maximize_mode_controller.cc

@@ -79,7 +79,7 @@ MaximizeModeController::MaximizeModeController()
       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
@@ -88,7 +88,7 @@ MaximizeModeController::MaximizeModeController()
 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

ash/wm/maximize_mode/maximize_mode_controller_unittest.cc

@@ -57,7 +57,7 @@ class MaximizeModeControllerTest : public test::AshTestBase {
 
   void SetUp() override {
     test::AshTestBase::SetUp();
-    Shell::GetInstance()->accelerometer_reader()->RemoveObserver(
+    chromeos::AccelerometerReader::GetInstance()->RemoveObserver(
         maximize_mode_controller());
 
     // Set the first display to be the internal display for the accelerometer
@@ -67,7 +67,7 @@ class MaximizeModeControllerTest : public test::AshTestBase {
   }
 
   void TearDown() override {
-    Shell::GetInstance()->accelerometer_reader()->AddObserver(
+    chromeos::AccelerometerReader::GetInstance()->AddObserver(
         maximize_mode_controller());
     test::AshTestBase::TearDown();
   }

athena/system/orientation_controller.cc

@@ -9,6 +9,7 @@
 #include "base/files/file_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/task_runner.h"
+#include "chromeos/accelerometer/accelerometer_reader.h"
 
 namespace athena {
 
@@ -24,18 +25,16 @@ OrientationController::OrientationController() {
 
 void OrientationController::InitWith(
     scoped_refptr<base::TaskRunner> blocking_task_runner) {
-  accelerometer_reader_.reset(new chromeos::AccelerometerReader());
-  accelerometer_reader_->Initialize(blocking_task_runner);
-  accelerometer_reader_->AddObserver(this);
+  chromeos::AccelerometerReader::GetInstance()->Initialize(
+      blocking_task_runner);
+  chromeos::AccelerometerReader::GetInstance()->AddObserver(this);
 }
 
 OrientationController::~OrientationController() {
-  DCHECK(!accelerometer_reader_.get());
 }
 
 void OrientationController::Shutdown() {
-  accelerometer_reader_->RemoveObserver(this);
-  accelerometer_reader_.reset();
+  chromeos::AccelerometerReader::GetInstance()->RemoveObserver(this);
 }
 
 void OrientationController::OnAccelerometerUpdated(

athena/system/orientation_controller.h

@@ -35,8 +35,6 @@ class OrientationController : public chromeos::AccelerometerReader::Observer {
   // The last configured rotation.
   gfx::Display::Rotation current_rotation_;
 
-  scoped_ptr<chromeos::AccelerometerReader> accelerometer_reader_;
-
   DISALLOW_COPY_AND_ASSIGN(OrientationController);
 };
 

chrome/browser/ui/ash/ash_init.cc

@@ -65,7 +65,7 @@ void OpenAsh(gfx::AcceleratedWidget remote_window) {
       scoped_ptr<ash::ScreenshotDelegate>(new ChromeScreenshotGrabber).Pass());
 #if defined(OS_CHROMEOS)
   // TODO(flackr): Investigate exposing a blocking pool task runner to chromeos.
-  shell->accelerometer_reader()->Initialize(
+  chromeos::AccelerometerReader::GetInstance()->Initialize(
       content::BrowserThread::GetBlockingPool()
           ->GetTaskRunnerWithShutdownBehavior(
               base::SequencedWorkerPool::SKIP_ON_SHUTDOWN));

chromeos/accelerometer/accelerometer_reader.cc

@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/files/file_util.h"
 #include "base/location.h"
+#include "base/memory/singleton.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
@@ -187,12 +188,9 @@ AccelerometerReader::ConfigurationData::ConfigurationData()
 AccelerometerReader::ConfigurationData::~ConfigurationData() {
 }
 
-AccelerometerReader::AccelerometerReader()
-    : configuration_(new AccelerometerReader::Configuration()),
-      weak_factory_(this) {
-}
-
-AccelerometerReader::~AccelerometerReader() {
+// static
+AccelerometerReader* AccelerometerReader::GetInstance() {
+  return Singleton<AccelerometerReader>::get();
 }
 
 void AccelerometerReader::Initialize(
@@ -224,6 +222,14 @@ bool AccelerometerReader::IsReadingStable(const ui::AccelerometerUpdate& update,
              kDeviationFromGravityThreshold;
 }
 
+AccelerometerReader::AccelerometerReader()
+    : configuration_(new AccelerometerReader::Configuration()),
+      weak_factory_(this) {
+}
+
+AccelerometerReader::~AccelerometerReader() {
+}
+
 void AccelerometerReader::OnInitialized(
     scoped_refptr<AccelerometerReader::Configuration> configuration,
     bool success) {

chromeos/accelerometer/accelerometer_reader.h

@@ -11,6 +11,9 @@
 #include "chromeos/chromeos_export.h"
 #include "ui/accelerometer/accelerometer_types.h"
 
+template <typename T>
+struct DefaultSingletonTraits;
+
 namespace base {
 class TaskRunner;
 }
@@ -54,8 +57,7 @@ class CHROMEOS_EXPORT AccelerometerReader {
     virtual ~Observer() {}
   };
 
-  AccelerometerReader();
-  ~AccelerometerReader();
+  static AccelerometerReader* GetInstance();
 
   void Initialize(scoped_refptr<base::TaskRunner> blocking_task_runner);
 
@@ -69,7 +71,13 @@ class CHROMEOS_EXPORT AccelerometerReader {
   static bool IsReadingStable(const ui::AccelerometerUpdate& update,
                               ui::AccelerometerSource source);
 
+ protected:
+  AccelerometerReader();
+  virtual ~AccelerometerReader();
+
  private:
+  friend struct DefaultSingletonTraits<AccelerometerReader>;
+
   // Dispatched when initialization is complete. If |success|, |configuration|
   // provides the details of the detected accelerometer.
   void OnInitialized(scoped_refptr<Configuration> configuration, bool success);