Refactors DeviceOrientation to make it more extensible

content/browser/device_orientation/provider.h

 // Copyright (c) 2012 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_DEVICE_ORIENTATION_PROVIDER_H_
 #define CONTENT_BROWSER_DEVICE_ORIENTATION_PROVIDER_H_
 
 #include "base/memory/ref_counted.h"
+#include "content/browser/device_orientation/device_data.h"
 #include "content/common/content_export.h"
 
 namespace device_orientation {
 
-class Orientation;
-
 class CONTENT_EXPORT Provider : public base::RefCountedThreadSafe<Provider> {
  public:
   class Observer {
    public:
-    // Called when the orientation changes.
+    // Called when device data changes.
     // An Observer must not synchronously call Provider::RemoveObserver
     // or Provider::AddObserver when this is called.
-    virtual void OnOrientationUpdate(const Orientation& orientation) = 0;
+    virtual void OnDeviceDataUpdate(const DeviceData* device_data) = 0;
+    DeviceData::DeviceDataType device_data_type() { return device_data_type_; }
 
    protected:
     virtual ~Observer() {}
+    // Each Observer observes exactly one type of DeviceData

[bulach, 2012/07/12 10:43:27]

nit: members must be private...
please, add a constructor that takes and sets this param. however, why is that
restriction? a single observer should be able to listen to multiple data types,
right?
perhaps it should be a param to "AddObserver" rather than in the observer
itself?

[aousterh, 2012/07/12 17:13:57]

Done (regarding the private members).

+    DeviceData::DeviceDataType device_data_type_;
   };
 
   // Returns a pointer to the singleton instance of this class.
   // The caller should store the returned pointer in a scoped_refptr.
   // The Provider instance is lazily constructed when GetInstance() is called,
   // and destructed when the last scoped_refptr referring to it is destructed.
   static Provider* GetInstance();
 
   // Inject a mock Provider for testing. Only a weak pointer to the injected
   // object will be held by Provider, i.e. it does not itself contribute to the
   // injected object's reference count.
   static void SetInstanceForTests(Provider* provider);
 
   // Get the current instance. Used for testing.
   static Provider* GetInstanceForTests();
 
-  // Note: AddObserver may call back synchronously to the observer with
-  // orientation data.
+  // Note: AddObserver may call back synchronously to the observer with data.
   virtual void AddObserver(Observer* observer) = 0;
   virtual void RemoveObserver(Observer* observer) = 0;
 
  protected:
   Provider();
   virtual ~Provider();
 
  private:
   friend class base::RefCountedThreadSafe<Provider>;
   static Provider* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(Provider);
 };
 
 }  // namespace device_orientation
 
 #endif  // CONTENT_BROWSER_DEVICE_ORIENTATION_PROVIDER_H_