DeviceOrientation API on ChromeOS

content/public/browser/sensor_manager_delegate_chromeos.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 CONTENT_PUBLIC_BROWSER_SENSOR_MANAGER_DELEGATE_CHROMEOS_H_
+#define CONTENT_PUBLIC_BROWSER_SENSOR_MANAGER_DELEGATE_CHROMEOS_H_
+
+#include "base/callback.h"
+#include "base/macros.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+typedef base::Callback<void(double x, double y, double z)>
+    OrientationDataCallback;
+
+// For platforms with a push API for accelerometer sensors this delegate can be

[Charlie Reis, 2014/12/10 01:02:41]

"For platforms with" vs "ChromeOS" in the class name seems inconsistent to me. 
I feel like we probably shouldn't mention ChromeOS in the class name if we keep
this.

+// implemented. Once notified to start fetching data, the callback provided can
+// be used to send the data.
+// TODO(jonross): Once accelerometer reading has been moved to
+// content/browser/device_sensors/ remove this delegate. Instead have
+// content/public/browser expose an observer for ChromeOS. (crbug.com/431865)

[Charlie Reis, 2014/12/10 01:02:41]

Avoiding this delegate in the public interface would be nice if possible.  Is
there a lot of work required for this?

[jonross, 2014/12/10 13:58:27]

It's a decent amount of work. I had been planning to address it in m-42 as that
move would directly conflict with some other in progress work.

[jam, 2014/12/10 21:57:05]

can you explain some more on what work is needed?

why can't this be directly implemented inside content?

[jonross, 2014/12/10 23:06:21]

My end goal is to have the ChromeOS accelerometer read within content/ and for
other libraries, such as ash/, that need the information to listen for changes.

Work that needs to be done:
chromeos/accelerometer/accelerometer_reader.h needs to be moved into
content/browser/device_sensors/

ash/accelerometer/accelerometer_controller.h needs to be replaced. I was
planning on having content/browser/device_sensors/sensor_manager_chromeos.h
replace the portion responsible for initializing AccelerometerReader. For the
portion that notifies observers, I was going to move that to a new class in
content/public/browser/, as ash/ still needs to listen for accelerometer events/

Currently the other ash code that uses the accelerometer is undergoing some
significant changes. I had planned to perform the accelerometer move after both
changes had landed in order to have it be one change, rather than having to
increase the complexity of either review.

The accelerometer code is also currently used in athena/ and I had yet to review
what changes are needed there, or if it can currently depend on content/

+class CONTENT_EXPORT SensorManagerDelegateChromeOS {
+ public:
+  virtual ~SensorManagerDelegateChromeOS();
+
+  // Allows platforms to provide a delegate.
+  static void SetDelegate(SensorManagerDelegateChromeOS* delegate);
+
+  // Start processing accelerometer events for orientation. The values can be
+  // passed via |callback|
+  virtual void StartFetchingDeviceOrientationData(
+      const OrientationDataCallback& callback) = 0;
+
+  // Stop processing accelerometer events for orientation.
+  virtual void StopFetchingDeviceOrientationData() = 0;
+
+ protected:
+  SensorManagerDelegateChromeOS();
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SensorManagerDelegateChromeOS);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_BROWSER_SENSOR_MANAGER_DELEGATE_CHROMEOS_H_