Fix TAP_DOWN gesture event:

ui/views/widget/widget.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/widget/widget.h"
 
 #include "base/logging.h"
 #include "base/message_loop.h"
 #include "base/utf_string_conversions.h"
 #include "ui/base/hit_test.h"
@@ skipping 1098 matching lines @@
 ui::GestureStatus Widget::OnGestureEvent(const GestureEvent& event) {
   ScopedEvent scoped(this, event);
   switch (event.type()) {
     case ui::ET_GESTURE_TAP_DOWN:
       is_touch_down_ = true;
       // We explicitly don't capture here. Not capturing enables multiple
       // widgets to get tap events at the same time. Views (such as tab
       // dragging) may explicitly capture.
       break;
 
-    case ui::ET_GESTURE_TAP_UP:
-      is_touch_down_ = false;
-      ReleaseCapture();
+    case ui::ET_GESTURE_END:
+      if (event.delta_x() == 1) {

[sky, 2012/06/07 02:43:54]

I don't understand the delta_x check? Why wouldn't we do this all the time?

[sadrul, 2012/06/07 03:04:55]

delta_x() means the number of active points for GESTURE_END. So if you have
three fingers down, releasing one of the fingers will generate a GESTURE_END
with delta_x() == 3. So GESTURE_END with delta_x() == 1 would imply that there
is currently no touch-down (and delta_x() > 1 implies at least some touch-point
is active)

(Naming this delta_x/delta_y is a bit unfortunate, and done for historical
reasons (to match with WebKit). These are planned to be fixed, eventually).

+        is_touch_down_ = false;
+        ReleaseCapture();
+      }
       break;
 
     default:
       break;
   }
   return GetRootView()->OnGestureEvent(event);
 }
 
 bool Widget::ExecuteCommand(int command_id) {
   return widget_delegate_->ExecuteWindowsCommand(command_id);
@@ skipping 154 matching lines @@
 
 ////////////////////////////////////////////////////////////////////////////////
 // internal::NativeWidgetPrivate, NativeWidget implementation:
 
 internal::NativeWidgetPrivate* NativeWidgetPrivate::AsNativeWidgetPrivate() {
   return this;
 }
 
 }  // namespace internal
 }  // namespace views