Make pinch zoom work on chromeos by setting touch id correctly

ui/events/ozone/evdev/event_factory_evdev.cc

 // Copyright 2014 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/ozone/evdev/event_factory_evdev.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/memory/ptr_util.h"
@@ skipping 317 matching lines @@
 void EventFactoryEvdev::DispatchTouchEvent(const TouchEventParams& params) {
   TRACE_EVENT1("evdev", "EventFactoryEvdev::DispatchTouchEvent", "device",
                params.device_id);
 
   gfx::PointF location = GetTransformedEventLocation(params);
   PointerDetails details = GetTransformedEventPointerDetails(params);
 
   // params.slot is guaranteed to be < kNumTouchEvdevSlots.
   int touch_id = touch_id_generator_.GetGeneratedID(
       params.device_id * kNumTouchEvdevSlots + params.slot);
+  details.id = touch_id;
   TouchEvent touch_event(
       params.type, gfx::Point(), modifiers_.GetModifierFlags(), touch_id,
       params.timestamp, /* radius_x */ 0.f, /* radius_y */ 0.f,
       /* angle */ 0.f, /* force */ 0.f);
   touch_event.set_location_f(location);
   touch_event.set_root_location_f(location);
   touch_event.set_source_device_id(params.device_id);
   touch_event.set_pointer_details(details);
   DispatchUiEvent(&touch_event);
 
@@ skipping 121 matching lines @@
 
   // Scan & monitor devices.
   device_manager_->AddObserver(this);
   device_manager_->ScanDevices(this);
 
   // Notify device thread that initial scan is done.
   input_device_factory_proxy_->OnStartupScanComplete();
 }
 
 }  // namespace ui