[Aura] Reduce frequency of PinchUpdate events.

ui/events/gesture_detection/scale_gesture_detector.h

Index: ui/events/gesture_detection/scale_gesture_detector.h
diff --git a/ui/events/gesture_detection/scale_gesture_detector.h b/ui/events/gesture_detection/scale_gesture_detector.h
index 08b62887c3a05ab137587ac2bc0cdf2cd8a975f8..99463953578bf03ea976f66146ea4af75eba68cb 100644
--- a/ui/events/gesture_detection/scale_gesture_detector.h
+++ b/ui/events/gesture_detection/scale_gesture_detector.h
@@ -33,6 +33,10 @@ class ScaleGestureDetector : public GestureDetector::SimpleGestureListener {
 
     // Whether double-tap drag scaling is enabled.
     bool quick_scale_enabled;
+
+    // Minimum pinch span change before pinch occurs (in dips). See
+    // crbug.com/373318.
+    float min_pinch_update_distance;

[jdduke (slow), 2014/05/21 19:30:37]

Maybe call this |min_pinch_update_span_delta|?

[tdresser, 2014/05/22 12:31:44]

Done.

   };
 
   class ScaleGestureListener {
@@ -140,6 +144,8 @@ class ScaleGestureDetector : public GestureDetector::SimpleGestureListener {
   float double_tap_focus_y_;
   DoubleTapMode double_tap_mode_;
 
+  float min_pinch_update_distance_;
+
   bool event_before_or_above_starting_gesture_event_;
 
   scoped_ptr<GestureDetector> gesture_detector_;