Moving input device hotplug event processing outside of ui/display

ui/events/device_data_manager.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 UI_EVENTS_DEVICE_DATA_MANAGER_H_
 #define UI_EVENTS_DEVICE_DATA_MANAGER_H_
 
 #include <stdint.h>
 
+#include <vector>
+
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
 #include "ui/events/events_base_export.h"
+#include "ui/events/touchscreen_device.h"
 #include "ui/gfx/transform.h"
 
 namespace ui {
 
+class InputDeviceEventObserver;
+
 // Keeps track of device mappings and event transformations.
 class EVENTS_BASE_EXPORT DeviceDataManager {
  public:
   virtual ~DeviceDataManager();
 
   static DeviceDataManager* GetInstance();
 
   void ClearTouchTransformerRecord();
   void UpdateTouchInfoForDisplay(int64_t display_id,
                                  int touch_device_id,
                                  const gfx::Transform& touch_transformer);
   void ApplyTouchTransformer(int touch_device_id, float* x, float* y);
   int64_t GetDisplayForTouchDevice(int touch_device_id) const;
 
+  void AddObserver(InputDeviceEventObserver* observer);
+  void RemoveObserver(InputDeviceEventObserver* observer);
+
+  virtual std::vector<TouchscreenDevice> GetTouchscreenDevices();

[Daniel Erat, 2014/06/17 21:59:18]

i think that there's still a general push to avoid non-interface inheritance in
chromium. how hard/messy would it be to restructure this class to e.g. be a pure
interface or call out to a passed-in object to get the touchscreen devices?

[dnicoara, 2014/06/20 17:01:05]

I've been talking to sadrul@ and rjkroege@ a bit about DDM. The plan is to mold
DDM into a nicer interface to allow Ozone to hook into it. Rob is going to add
better Ozone support, so I think I'll wait until he makes more progress before
getting this CL into its final form. (I'll work on updating the unittests in the
meantime)

+
  protected:
   DeviceDataManager();
 
   static DeviceDataManager* instance_;
 
   bool IsTouchDeviceIdValid(int touch_device_id) const;
 
   static const int kMaxDeviceNum = 128;
 
   // Table to keep track of which display id is mapped to which touch device.
   int64_t touch_device_to_display_map_[kMaxDeviceNum];
   // Index table to find the TouchTransformer for a touch device.
   gfx::Transform touch_device_transformer_map_[kMaxDeviceNum];
 
+  ObserverList<InputDeviceEventObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(DeviceDataManager);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_DEVICE_DATA_MANAGER_H_