Adding momentum/overscroll to views:: ScrollViews

ui/events/event_constants.h

Index: ui/events/event_constants.h
diff --git a/ui/events/event_constants.h b/ui/events/event_constants.h
index 664e837f271193af2b8d07197d3a0cec2fcc3866..2061d5429358c828126d6a71e26d6cdfa9a6e6a2 100644
--- a/ui/events/event_constants.h
+++ b/ui/events/event_constants.h
@@ -160,6 +160,21 @@ enum EventPhase {
   EP_POSTDISPATCH
 };
 
+enum EventMomentumPhase {
+  // Event stream can not result in momentum, or is a non-momentum update to an
+  // event stream already begun.
+  EM_PHASE_NONE = 0,
+
+  // Event is the beginning of an event stream that may result in momentum.
+  EM_PHASE_MAY_BEGIN = 0x1,
+
+  // Event is an update while in a momentum phase.
+  EM_PHASE_INERTIAL_UPDATE = 0x2,
+
+  // Event marks the end of the current event stream.
+  EM_PHASE_END = 0x4,
+};
+
 // Device ID for Touch and Key Events.
 enum EventDeviceId {
   ED_UNKNOWN_DEVICE = -1