Add id properties to PointerEvent

ui/events/blink/web_input_event_builders_win.cc

 // Copyright 2016 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/events/blink/web_input_event_builders_win.h"
 
 #include "ui/display/win/screen_win.h"
 #include "ui/events/blink/blink_event_util.h"
 #include "ui/events/event_utils.h"
 
@@ skipping 149 matching lines @@
   if (wparam & MK_LBUTTON)
     modifiers |= WebInputEvent::LeftButtonDown;
   if (wparam & MK_MBUTTON)
     modifiers |= WebInputEvent::MiddleButtonDown;
   if (wparam & MK_RBUTTON)
     modifiers |= WebInputEvent::RightButtonDown;
 
   WebMouseEvent result(type, modifiers, time_stamp);
   result.pointerType = pointer_type;
   result.button = button;
+  result.id = ui::PointerEvent::kMousePointerId;

[mustaq, 2017/02/27 16:02:26]

Are we sure that stylus events are not going through this? Hardcoded ids could
cause problems with stylus ids, even after we migrate to WM_POINTER events
because legacy systems could still pass stylus events as WM_MOUSE events.

 
   // set position fields:
-
   result.x = static_cast<short>(LOWORD(lparam));
   result.y = static_cast<short>(HIWORD(lparam));
   result.windowX = result.x;
   result.windowY = result.y;
 
   POINT global_point = {result.x, result.y};
   ClientToScreen(hwnd, &global_point);
 
   // We need to convert the global point back to DIP before using it.
   gfx::Point dip_global_point = display::win::ScreenWin::ScreenToDIPPoint(
@@ skipping 182 matching lines @@
     result.wheelTicksX = wheel_delta;
   } else {
     result.deltaY = scroll_delta;
     result.wheelTicksY = wheel_delta;
   }
 
   return result;
 }
 
 }  // namespace ui