x11: Use kernel timestamps for touch events (if available).

ui/base/x/valuators.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_BASE_X_VALUATORS_H_
 #define UI_BASE_X_VALUATORS_H_
 
 #include "base/basictypes.h"
 
 template <typename T> struct DefaultSingletonTraits;
@@ skipping 36 matching lines @@
     VAL_SLOT_ID,           // ID of the finger that triggered a touch event
                            // (useful when tracking multiple simultaneous
                            // touches)
 #endif
     // NOTE for XInput MT: 'Tracking ID' is provided in every touch event to
     // track individual touch. 'Tracking ID' is an unsigned 32-bit value and
     // is increased for each new touch. It will wrap back to 0 when reaching
     // the numerical limit.
     VAL_TRACKING_ID,       // ID of the touch point.
 
+    // Kernel timestamp from touch screen (if available).
+    VAL_TOUCH_RAW_TIMESTAMP,
+
     VAL_LAST_ENTRY
   };
 
   // Returns the ValuatorTracker singleton.
   static ValuatorTracker* GetInstance();
 
   // Extract the Valuator from the XEvent. Return true and the value is set
   // if the Valuator is found, false and value unchanged if the Valuator
   // is not found.
   bool ExtractValuator(const XEvent& xev, Valuator val, float* value);
@@ skipping 37 matching lines @@
   // a device. Defaults to 0 if the valuator was not specified in an earlier
   // event.
   float last_seen_valuator_[kMaxDeviceNum][VAL_LAST_ENTRY];
 
   DISALLOW_COPY_AND_ASSIGN(ValuatorTracker);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_X_VALUATORS_H_