Ensure grouped touch events have a common timestamp on Windows

ui/views/win/hwnd_message_handler.cc

 // 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.
 
 #include "ui/views/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <oleacc.h>
 #include <shellapi.h>
 
@@ skipping 2290 matching lines @@
   tracked_objects::ScopedTracker tracking_profile(
       FROM_HERE_WITH_EXPLICIT_FUNCTION(
           "440919 HWNDMessageHandler::OnTouchEvent"));
 
   // Handle touch events only on Aura for now.
   int num_points = LOWORD(w_param);
   scoped_ptr<TOUCHINPUT[]> input(new TOUCHINPUT[num_points]);
   if (ui::GetTouchInputInfoWrapper(reinterpret_cast<HTOUCHINPUT>(l_param),
                                    num_points, input.get(),
                                    sizeof(TOUCHINPUT))) {
+    // input[i].dwTime doesn't necessarily relate to the system time at all,
+    // so use base::TimeTicks::Now().
+    const base::TimeTicks event_time = base::TimeTicks::Now();
     int flags = ui::GetModifiersFromKeyState();
     TouchEvents touch_events;
     for (int i = 0; i < num_points; ++i) {
       POINT point;
       point.x = TOUCH_COORD_TO_PIXEL(input[i].x);
       point.y = TOUCH_COORD_TO_PIXEL(input[i].y);
 
       if (base::win::GetVersion() == base::win::VERSION_WIN7) {
         // Windows 7 sends touch events for touches in the non-client area,
         // whereas Windows 8 does not. In order to unify the behaviour, always
@@ skipping 20 matching lines @@
             base::Bind(&HWNDMessageHandler::ResetTouchDownContext,
                        weak_factory_.GetWeakPtr()),
             base::TimeDelta::FromMilliseconds(kTouchDownContextResetTimeout));
       } else if (input[i].dwFlags & TOUCHEVENTF_UP) {
         touch_ids_.erase(input[i].dwID);
         touch_event_type = ui::ET_TOUCH_RELEASED;
       } else if (input[i].dwFlags & TOUCHEVENTF_MOVE) {
         touch_event_type = ui::ET_TOUCH_MOVED;
       }
       if (touch_event_type != ui::ET_UNKNOWN) {
-        // input[i].dwTime doesn't necessarily relate to the system time at all,
-        // so use base::TimeTicks::Now()
-        const base::TimeTicks now = base::TimeTicks::Now();
         ui::TouchEvent event(touch_event_type,
                              gfx::Point(point.x, point.y),
                              id_generator_.GetGeneratedID(input[i].dwID),
-                             now - base::TimeTicks());
+                             event_time - base::TimeTicks());
         event.set_flags(flags);
         event.latency()->AddLatencyNumberWithTimestamp(
             ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
             0,
             0,
-            base::TimeTicks::FromInternalValue(
-                event.time_stamp().ToInternalValue()),
+            event_time,
             1);
 
         touch_events.push_back(event);
         if (touch_event_type == ui::ET_TOUCH_RELEASED)
           id_generator_.ReleaseNumber(input[i].dwID);
       }
     }
     // Handle the touch events asynchronously. We need this because touch
     // events on windows don't fire if we enter a modal loop in the context of
     // a touch event.
@@ skipping 368 matching lines @@
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_HIDEWINDOW);
     SetWindowPos(hwnd(), NULL, 0, 0, 0, 0, flags | SWP_SHOWWINDOW);
   }
   // WM_DWMCOMPOSITIONCHANGED is only sent to top level windows, however we want
   // to notify our children too, since we can have MDI child windows who need to
   // update their appearance.
   EnumChildWindows(hwnd(), &SendDwmCompositionChanged, NULL);
 }
 
 }  // namespace views