Plumb maxTouchPoints for AuraX11

ui/events/x/touch_factory_x11.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 UI_EVENTS_X_TOUCH_FACTORY_X11_H_
 #define UI_EVENTS_X_TOUCH_FACTORY_X11_H_
 
 #include <bitset>
 #include <map>
 #include <vector>
@@ skipping 54 matching lines @@
   // Tries to find an existing slot ID mapping to tracking ID. If there
   // isn't one already, allocates a new slot ID and sets up the mapping.
   int GetSlotForTrackingID(uint32 tracking_id);
 
   // Releases the slot ID mapping to tracking ID.
   void ReleaseSlotForTrackingID(uint32 tracking_id);
 
   // Whether any touch device is currently present and enabled.
   bool IsTouchDevicePresent();
 
+  // Return maximum simultaneous touch points supported by device.
+  int GetMaxTouchPoints() const;
+
   // Sets up the device id in the list |devices| as multi-touch capable
   // devices and enables touch events processing. This function is only
   // for test purpose, and it does not query from X server.
   void SetTouchDeviceForTest(const std::vector<unsigned int>& devices);
 
  private:
   // Requirement for Singleton
   friend struct DefaultSingletonTraits<TouchFactory>;
 
   // NOTE: To keep track of touch devices, we currently maintain a lookup table
@@ skipping 18 matching lines @@
   // Indicates whether touch events are explicitly disabled.
   bool touch_events_disabled_;
 
   // The list of touch devices. For testing/debugging purposes, a single-pointer
   // device (mouse or touch screen without sufficient X/driver support for MT)
   // can sometimes be treated as a touch device. The key in the map represents
   // the device id, and the value represents if the device is multi-touch
   // capable.
   std::map<int, bool> touch_device_list_;
 
-  // Maximum simultaneous touch points.
-  static const int kMaxTouchPoints = 32;
+  // Maximum simultaneous touch points supported by device. In the case of
+  // devices with multiple digitizers (e.g. multiple touchscreens), the value
+  // is the maximum of the set of maximum supported contacts by each individual
+  // digitizer.
+  int max_touch_points_;
 
   SequentialIDGenerator id_generator_;
 
   DISALLOW_COPY_AND_ASSIGN(TouchFactory);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_X_TOUCH_FACTORY_X11_H_