Support minimum gesture bounds in GestureProvider

ui/events/gesture_event_details.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/gesture_event_details.h"
 
 namespace ui {
 
 GestureEventDetails::GestureEventDetails() : type_(ET_UNKNOWN) {}
 
 GestureEventDetails::GestureEventDetails(ui::EventType type,
                                          float delta_x,
                                          float delta_y)
     : type_(type),
       touch_points_(1) {
+  DCHECK_GE(type, ET_GESTURE_TYPE_START);
+  DCHECK_LE(type, ET_GESTURE_TYPE_END);
   switch (type_) {
     case ui::ET_GESTURE_SCROLL_BEGIN:
       data.scroll_begin.x_hint = delta_x;
       data.scroll_begin.y_hint = delta_y;
       break;
 
     case ui::ET_GESTURE_SCROLL_UPDATE:
       data.scroll_update.x = delta_x;
       data.scroll_update.y = delta_y;
       break;
@@ skipping 34 matching lines @@
       }
       break;
   }
 }
 
 GestureEventDetails::Details::Details() {
   memset(this, 0, sizeof(Details));
 }
 
 }  // namespace ui