Suppressed MEs for gestures from cancelled PEs

third_party/WebKit/public/web/WebInputEvent.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 477 matching lines @@
         UnknownMomentumPhase = 0, // No phase information.
         NonMomentumPhase, // Regular scrolling phase.
         MomentumPhase, // Momentum phase.
     };
 
     int x;
     int y;
     int globalX;
     int globalY;
     WebGestureDevice sourceDevice;
+
+    // If the WebGestureEvent has sourceDevice=WebGestureDeviceTouchscreen, this
+    // field contains the unique identifier for the touch event that triggered

[Rick Byers, 2016/06/03 15:31:40]

please define a bit more precisely WHICH touch event this corresponds to
("triggers" is pretty vague).  Eg. for a GestureScrollUpdate is it the
touchmove?  What about for a GestureLongPress?  Is it "the ID of the most recent
event which, if cancelled, would have suppressed the generation of this gesture
event"?

This might get a little hairy in the general case.  You could perhaps avoid the
confusion/complexity by saying it represents the entire sequence (not a specific
event) and does so by referring to the event ID for the touchstart of the first
finger involved in the gesture.  This might be more work to implement on the
content side though.

[mustaq, 2016/06/03 20:34:45]

Does the comment sound better now? This is set on releasing the GE from TDGF, so
"trigger" wasn't the right word.

+    // the gesture. Otherwise, it contains 0.
+    uint32_t uniqueTouchEventId;
+
     // This field exists to allow BrowserPlugin to mark GestureScroll events as
     // 'resent' to handle the case where an event is not consumed when first
     // encountered; it should be handled differently by the plugin when it is
     // sent for thesecond time. No code within Blink touches this, other than to
     // plumb it through event conversions.
     int resendingPluginId;
 
     union {
         // Tap information must be set for GestureTap, GestureTapUnconfirmed,
         // and GestureDoubleTap events.
@@ skipping 145 matching lines @@
         , uniqueTouchEventId(0)
     {
     }
 };
 
 #pragma pack(pop)
 
 } // namespace blink
 
 #endif