Consuming a touch move prevents only the next scroll update.

content/browser/renderer_host/input/gesture_event_packet.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 CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURE_EVENT_PACKET_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURE_EVENT_PACKET_H_
 
 #include "content/common/content_export.h"
 #include "third_party/WebKit/public/web/WebInputEvent.h"
 
 namespace content {
 
 // Acts as a transport container for gestures created (directly or indirectly)
 // by a touch event.
 class CONTENT_EXPORT GestureEventPacket {
  public:
   enum GestureSource {
-    INVALID = -1,  // Used only for a default-constructed packet..
-    TOUCH_BEGIN,   // The start of a new gesture sequence.
-    TOUCH,         // Continuation of an existing gesture sequence.
-    TOUCH_TIMEOUT, // Timeout from an existing gesture sequence.
+    INVALID = -1,          // Used only for a default-constructed packet.
+    OUT_OF_ORDER,          // The source of the gesture was out of order.
+    TOUCH_SEQUENCE_BEGIN,  // The start of a new gesture sequence.
+    TOUCH_SEQUENCE_END,    // The end of gesture sequence.

[tdresser, 2014/02/13 18:14:09]

This isn't currently used, but will likely be in the future. Should I strip it
out for now?

[jdduke (slow), 2014/02/13 19:40:00]

Hmm, I suppose it doesn't hurt if for no other reason than consistency.

+    TOUCH_BEGIN,           // A touch down occured during a gesture sequence.
+    TOUCH_MOVE,            // A touch move occured during a gesture sequence.
+    TOUCH_END,             // A touch up occured during a gesture sequence.
+    TOUCH_TIMEOUT,         // Timeout from an existing gesture sequence.
   };
 
   GestureEventPacket();
   ~GestureEventPacket();
 
   // Factory methods for creating a packet from a particular event.
   static GestureEventPacket FromTouch(const blink::WebTouchEvent& event);
   static GestureEventPacket FromTouchTimeout(
       const blink::WebGestureEvent& event);
 
   void Push(const blink::WebGestureEvent& gesture);
 
   const blink::WebGestureEvent& gesture(size_t i) const { return gestures_[i]; }
   size_t gesture_count() const { return gesture_count_; }
   GestureSource gesture_source() const { return gesture_source_; }
 
 private:
   explicit GestureEventPacket(GestureSource source);
 
   enum { kMaxGesturesPerTouch = 5 };
   blink::WebGestureEvent gestures_[kMaxGesturesPerTouch];
   size_t gesture_count_;
   GestureSource gesture_source_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_INPUT_GESTURE_EVENT_PACKET_H_