Add scroll units in GestureEvents.

third_party/WebKit/public/web/WebInputEvent.h

Index: third_party/WebKit/public/web/WebInputEvent.h
diff --git a/third_party/WebKit/public/web/WebInputEvent.h b/third_party/WebKit/public/web/WebInputEvent.h
index 6ce0fea97533c50f0eb52c316560f57b4fac0b41..c08c8a29c09f38b3483c48cb799a8f89e21ee0e2 100644
--- a/third_party/WebKit/public/web/WebInputEvent.h
+++ b/third_party/WebKit/public/web/WebInputEvent.h
@@ -456,6 +456,12 @@ public:
 
 class WebGestureEvent : public WebInputEvent {
 public:
+    enum ScrollUnits {
+        PrecisePixels = 0, // generated by high precision devices.
+        Pixels, // large pixel jump duration; should animate to delta.
+        Page // page (visible viewport) based scrolling.
+    };
+
     int x;
     int y;
     int globalX;
@@ -502,6 +508,7 @@ public:
             // May be redundant with deltaX/deltaY in the first scrollUpdate.
             float deltaXHint;
             float deltaYHint;
+            unsigned deltaHintUnits : 3;

[tdresser, 2016/01/05 16:07:33]

It might be worth commenting that the default of 0 is PrecisePixels (and below)

[dtapuska, 2016/01/05 16:52:28]

Done.

             // If true, this event will skip hit testing to find a scroll
             // target and instead just scroll the viewport.
             bool targetViewport;
@@ -520,6 +527,7 @@ public:
             bool previousUpdateInSequencePrevented;
             bool preventPropagation;
             bool inertial;
+            unsigned deltaUnits : 3;
         } scrollUpdate;
 
         struct {