ozone: Map TouchEvent::touch_id_ into expected range

ui/aura/window_event_dispatcher.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/aura/window_event_dispatcher.h"
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/trace_event/trace_event.h"
@@ skipping 57 matching lines @@
   return false;
 }
 
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
 // WindowEventDispatcher, public:
 
 WindowEventDispatcher::WindowEventDispatcher(WindowTreeHost* host)
     : host_(host),
-      touch_ids_down_(0),
       mouse_pressed_handler_(NULL),
       mouse_moved_handler_(NULL),
       event_dispatch_target_(NULL),
       old_dispatch_target_(NULL),
       synthesize_mouse_move_(false),
       move_hold_count_(0),
       dispatching_held_event_(nullptr),
       observer_manager_(this),
       repost_event_factory_(this),
       held_event_factory_(this) {
@@ skipping 757 matching lines @@
       break;
   }
 
   PreDispatchLocatedEvent(target, event);
 }
 
 void WindowEventDispatcher::PreDispatchTouchEvent(Window* target,
                                                   ui::TouchEvent* event) {
   switch (event->type()) {
     case ui::ET_TOUCH_PRESSED:
-      touch_ids_down_ |= (1 << event->touch_id());
-      Env::GetInstance()->set_touch_down(touch_ids_down_ != 0);
+      touch_ids_down_.insert(event->touch_id());
+      Env::GetInstance()->set_touch_down(!touch_ids_down_.empty());
       break;
 
       // Handle ET_TOUCH_CANCELLED only if it has a native event.
     case ui::ET_TOUCH_CANCELLED:
       if (!event->HasNativeEvent())
         break;
       // fallthrough
     case ui::ET_TOUCH_RELEASED:
-      touch_ids_down_ = (touch_ids_down_ | (1 << event->touch_id())) ^
-            (1 << event->touch_id());
-      Env::GetInstance()->set_touch_down(touch_ids_down_ != 0);
+      touch_ids_down_.erase(event->touch_id());
+      Env::GetInstance()->set_touch_down(!touch_ids_down_.empty());
       break;
 
     case ui::ET_TOUCH_MOVED:
       if (move_hold_count_ && !dispatching_held_event_) {
         held_move_event_.reset(new ui::TouchEvent(*event, target, window()));
         event->SetHandled();
         return;
       }
       break;
 
@@ skipping 12 matching lines @@
   }
 
   // This flag is set depending on the gestures recognized in the call above,
   // and needs to propagate with the forwarded event.
   event->set_may_cause_scrolling(orig_event.may_cause_scrolling());
 
   PreDispatchLocatedEvent(target, event);
 }
 
 }  // namespace aura