Fix mouse wheel over-scrolls when display is scaled and scroll is paginated

ui/events/blink/blink_event_util.cc

Index: ui/events/blink/blink_event_util.cc
diff --git a/ui/events/blink/blink_event_util.cc b/ui/events/blink/blink_event_util.cc
index 6378ce21ff9968ecc7e1652a547c9d451f982fbf..4143e078ba2f9f3c6a4909430f0a07d2af862f32 100644
--- a/ui/events/blink/blink_event_util.cc
+++ b/ui/events/blink/blink_event_util.cc
@@ -750,8 +750,10 @@ std::unique_ptr<blink::WebInputEvent> TranslateAndScaleWebInputEvent(
     wheel_event->y += delta.y();
     wheel_event->x *= scale;
     wheel_event->y *= scale;
-    wheel_event->deltaX *= scale;
-    wheel_event->deltaY *= scale;
+    if (!wheel_event->scrollByPage) {
+      wheel_event->deltaX *= scale;
+      wheel_event->deltaY *= scale;
+    }
     wheel_event->wheelTicksX *= scale;

[aelias_OOO_until_Jul13, 2017/02/16 22:11:13]

I think wheel tick count should be within the if block as well.

[chengx, 2017/02/17 08:26:02]

Done.

     wheel_event->wheelTicksY *= scale;
   } else if (blink::WebInputEvent::isMouseEventType(event.type())) {
@@ -788,12 +790,18 @@ std::unique_ptr<blink::WebInputEvent> TranslateAndScaleWebInputEvent(
     gesture_event->y *= scale;
     switch (gesture_event->type()) {
       case blink::WebInputEvent::GestureScrollUpdate:
-        gesture_event->data.scrollUpdate.deltaX *= scale;
-        gesture_event->data.scrollUpdate.deltaY *= scale;
+        if (gesture_event->data.scrollUpdate.deltaUnits !=
+            blink::WebGestureEvent::ScrollUnits::Page) {
+          gesture_event->data.scrollUpdate.deltaX *= scale;
+          gesture_event->data.scrollUpdate.deltaY *= scale;
+        }
         break;
       case blink::WebInputEvent::GestureScrollBegin:
-        gesture_event->data.scrollBegin.deltaXHint *= scale;
-        gesture_event->data.scrollBegin.deltaYHint *= scale;
+        if (gesture_event->data.scrollBegin.deltaHintUnits !=
+            blink::WebGestureEvent::ScrollUnits::Page) {
+          gesture_event->data.scrollBegin.deltaXHint *= scale;
+          gesture_event->data.scrollBegin.deltaYHint *= scale;
+        }
         break;
 
       case blink::WebInputEvent::GesturePinchUpdate: