Support minimum gesture bounds in GestureProvider

ui/events/gesture_event_details.h

 // 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.
 
 #ifndef UI_EVENTS_GESTURE_DETECTION_GESTURE_EVENT_DETAILS_H_
 #define UI_EVENTS_GESTURE_DETECTION_GESTURE_EVENT_DETAILS_H_
 
 #include "base/logging.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/events_base_export.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/rect_conversions.h"
 
 namespace ui {
 
 struct EVENTS_BASE_EXPORT GestureEventDetails {
  public:
   GestureEventDetails();
   GestureEventDetails(EventType type, float delta_x, float delta_y);
 
   EventType type() const { return type_; }
 
   int touch_points() const { return touch_points_; }
-  void set_touch_points(int touch_points) { touch_points_ = touch_points; }
+  void set_touch_points(int touch_points) {
+    DCHECK_GT(touch_points, 0);
+    touch_points_ = touch_points;
+  }
 
   // TODO(tdresser): Return RectF. See crbug.com/337824.
   const gfx::Rect bounding_box() const {
     return ToEnclosingRect(bounding_box_);
   }
 
   const gfx::RectF& bounding_box_f() const {
     return bounding_box_;
   }
 
@@ skipping 65 matching lines @@
   }
 
   int tap_count() const {
     DCHECK(type_ == ET_GESTURE_TAP ||
            type_ == ET_GESTURE_TAP_UNCONFIRMED ||
            type_ == ET_GESTURE_DOUBLE_TAP);
     return data.tap_count;
   }
 
   void set_tap_count(int tap_count) {
+    DCHECK_GE(tap_count, 0);
     DCHECK(type_ == ET_GESTURE_TAP ||
            type_ == ET_GESTURE_TAP_UNCONFIRMED ||
            type_ == ET_GESTURE_DOUBLE_TAP);
     data.tap_count = tap_count;
   }
 
  private:
   EventType type_;
   union Details {
     Details();
@@ skipping 38 matching lines @@
   int touch_points_;  // Number of active touch points in the gesture.
 
   // Bounding box is an axis-aligned rectangle that contains all the
   // enclosing rectangles of the touch-points in the gesture.
   gfx::RectF bounding_box_;
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURE_DETECTION_GESTURE_EVENT_DETAILS_H_