Read and expose accelerometer values from cros-ec-accel trigger.

ash/accelerometer/accelerometer_controller.h

+// 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.
+
+#ifndef ASH_ACCELEROMETER_ACCELEROMETER_CONTROLLER_H_
+#define ASH_ACCELEROMETER_ACCELEROMETER_CONTROLLER_H_
+
+#include "base/observer_list.h"
+
+#if defined(OS_CHROMEOS)
+#include "chromeos/accelerometer/accelerometer_reader.h"
+#endif
+
+namespace gfx {
+class Vector3dF;
+}
+
+namespace ash {
+
+class AccelerometerObserver;
+
+// This class owns the communication interface for talking to the accelerometer
+// on supporting devices. Observers will be delivered OnAccelerometerRead
+// notifications if an accelerometer was detected.

[Daniel Erat, 2014/03/26 22:26:14]

(just wondering; might not be necessary yet): do observers need to be able to
tell whether an accelerometer is present or not?

[flackr, 2014/03/27 15:21:07]

Not yet, I have patches for auto entering touch view and rotation and both of
those only do something if they receive events and if not maintain the default
behavior (i.e. no screen rotation or touchview).

+class AccelerometerController
+#if defined(OS_CHROMEOS)
+    : public chromeos::AccelerometerDelegate {
+#else
+    {
+#endif
+ public:
+  AccelerometerController();
+  virtual ~AccelerometerController();
+
+  // Add/remove observer.
+  void AddObserver(AccelerometerObserver* observer);
+  void RemoveObserver(AccelerometerObserver* observer);
+
+  // chromeos::AccelerometerDelegate:
+  virtual void OnAccelerometerRead(const gfx::Vector3dF& base,

[Daniel Erat, 2014/03/26 22:26:14]

this may just be my own personal convention, but i usually like to give
delegates' methods specific, imperative names (e.g.
NotifyObserversAboutAccelerometerReading or perhaps
HandleAccelerometerReading/Read) and let observer interfaces use open-ended
names like OnAccelerometerRead.

[flackr, 2014/03/27 15:21:07]

Done.

+                                   const gfx::Vector3dF& lid) OVERRIDE;
+ private:
+#if defined(OS_CHROMEOS)
+  // The AccelerometerReader which directly triggers and reads from the
+  // accelerometer device.
+  chromeos::AccelerometerReader reader_;
+#endif
+
+  ObserverList<AccelerometerObserver, true> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(AccelerometerController);
+};
+
+}  // namespace ash
+
+#endif  // ASH_ACCELEROMETER_ACCELEROMETER_CONTROLLER_H_