Initial sensor event provider for testing views screen rotation

content/browser/sensors/sensors_provider_impl.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_IMPL_H_

[tfarina, 2011/07/25 14:57:52]

CONTENT_BROWSER_SENSORS_SENSORS_PROVIDER_IMPL_H_

+#define CONTENT_BROWSER_SENSORS_PROVIDER_IMPL_H_
+#pragma once
+
+#include "base/memory/ref_counted.h"
+#include "base/observer_list_threadsafe.h"
+#include "content/browser/sensors/sensors_provider.h"
+
+template <typename T> struct DefaultSingletonTraits;
+
+namespace sensors {
+
+class ProviderImpl : public Provider {
+ public:
+  static ProviderImpl* GetInstance();
+
+  // Provider implementation
+  virtual void AddListener(Listener* listener) OVERRIDE;

[tfarina, 2011/07/25 14:57:52]

It's more common to have this named:

AddObserver(Observer* observer);

[cwolfe, 2011/07/25 15:49:45]

Differences coming in later revisions. Most notably, that listeners subscribe to
specific channels of the sensors providers, rather than observing all messages.

+  virtual void RemoveListener(Listener* listener) OVERRIDE;
+  virtual void ScreenOrientationChanged(const ScreenOrientation& change)

[tfarina, 2011/07/25 14:57:52]

move this to the line below so you don't leave OVERRIDE alone. This is something
that Scott (sky) prefers and it's like what we do with "const". Also there is a
thread about this on chromium-dev mailing list.

+      OVERRIDE;
+
+ private:
+  friend struct DefaultSingletonTraits<ProviderImpl>;
+
+  ProviderImpl();
+  virtual ~ProviderImpl();
+
+  typedef ObserverListThreadSafe<Listener> ListenerList;
+  scoped_refptr<ListenerList> listeners_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProviderImpl);
+};
+
+}  // namespace sensors
+
+DISABLE_RUNNABLE_METHOD_REFCOUNT(sensors::ProviderImpl);

[tfarina, 2011/07/25 14:57:52]

Add a comment explaining why you need this?

+
+#endif  // CONTENT_BROWSER_SENSORS_PROVIDER_IMPL_H_