Move touchscreen device caching to DeviceDataManager

ui/events/device_data_manager.h

Index: ui/events/device_data_manager.h
diff --git a/ui/events/device_data_manager.h b/ui/events/device_data_manager.h
index 838ce67210f1dc669e9cbc079d46967e4be34293..aae827204cc5e7e11aae927a68e244c587cb5469 100644
--- a/ui/events/device_data_manager.h
+++ b/ui/events/device_data_manager.h
@@ -7,15 +7,22 @@
 
 #include <stdint.h>
 
+#include <vector>
+
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/observer_list.h"
+#include "ui/events/device_hotplug_event_observer.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 {
+class EVENTS_BASE_EXPORT DeviceDataManager : public DeviceHotplugEventObserver {
  public:
   virtual ~DeviceDataManager();
 
@@ -33,6 +40,13 @@ class EVENTS_BASE_EXPORT DeviceDataManager {
   void UpdateTouchRadiusScale(int touch_device_id, double scale);
   void ApplyTouchRadiusScale(int touch_device_id, double* radius);
 
+  const std::vector<TouchscreenDevice>& touchscreen_devices() const {
+    return touchscreen_devices_;
+  }
+
+  void AddObserver(InputDeviceEventObserver* observer);
+  void RemoveObserver(InputDeviceEventObserver* observer);
+
  protected:
   DeviceDataManager();
 
@@ -45,6 +59,10 @@ class EVENTS_BASE_EXPORT DeviceDataManager {
 
   bool IsTouchDeviceIdValid(int touch_device_id) const;
 
+  // DeviceHotplugEventObserver:
+  virtual void OnTouchscreenDevicesUpdated(
+      const std::vector<TouchscreenDevice>& devices) OVERRIDE;
+
   double touch_radius_scale_map_[kMaxDeviceNum];
 
   // Table to keep track of which display id is mapped to which touch device.
@@ -52,6 +70,10 @@ class EVENTS_BASE_EXPORT DeviceDataManager {
   // Index table to find the TouchTransformer for a touch device.
   gfx::Transform touch_device_transformer_map_[kMaxDeviceNum];
 
+  std::vector<TouchscreenDevice> touchscreen_devices_;
+
+  ObserverList<InputDeviceEventObserver> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(DeviceDataManager);
 };