Initial sensor event provider for testing views screen rotation

content/browser/sensors/sensors_provider.h

+// Copyright (c) 2011 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_BROWSER_SENSORS_PROVIDER_H_
+#define CONTENT_BROWSER_SENSORS_PROVIDER_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include "content/common/sensors_listener.h"
+
+// The sensors API will unify various types of sensor data into a set of
+// channels, each of which provides change events and periodic updates.
+//
+// This version of the API is intended only to support the experimental screen
+// rotation code and is not for general use. In particular, the final listener
+// will declare generic |OnSensorChanged| and |OnSensorUpdated| methods, rather
+// than the special-purpose |OnScreenOrientationChanged|.
+
+namespace sensors {
+
+// TODO(cwolfe): Finish defining the initial set of channels and replace this
+// with the generic sensor provider.
+//
+class Provider {
+ public:
+  static Provider* GetInstance();
+
+  // Adds a sensor listener. The listener will receive callbacks to indicate
+  // sensor changes and updates until it is removed.
+  //
+  // This method may be called in any thread. Callbacks on a listener will
+  // always be executed in the thread which added that listener.
+  virtual void AddListener(Listener* listener) = 0;
+
+  // Removes a sensor listener.
+  //
+  // This method must be called in the same thread which added the listener.
+  // If the listener is not currently subscribed, this method may be called in
+  // any thread.
+  virtual void RemoveListener(Listener* listener) = 0;
+
+  // Broadcasts a change to the coarse screen orientation.
+  //
+  // This method may be called in any thread.
+  virtual void ScreenOrientationChanged(const ScreenOrientation& change) = 0;
+
+ protected:
+  Provider();
+  virtual ~Provider();
+
+  DISALLOW_COPY_AND_ASSIGN(Provider);
+};
+
+}  // namespace sensors
+
+#endif  // CONTENT_BROWSER_SENSORS_PROVIDER_H_