Add scroll units in GestureEvents.

third_party/WebKit/Source/core/input/EventHandler.cpp

Index: third_party/WebKit/Source/core/input/EventHandler.cpp
diff --git a/third_party/WebKit/Source/core/input/EventHandler.cpp b/third_party/WebKit/Source/core/input/EventHandler.cpp
index 47861ee82accc725137fb84ebbac9b5d1eb3bf63..131ab4313a92302de30861c2ad0436439428fab7 100644
--- a/third_party/WebKit/Source/core/input/EventHandler.cpp
+++ b/third_party/WebKit/Source/core/input/EventHandler.cpp
@@ -2505,6 +2505,15 @@ WebInputEventResult EventHandler::handleGestureScrollUpdate(const PlatformGestur
     if (delta.isZero())
         return WebInputEventResult::NotHandled;
 
+    ScrollGranularity granularity = gestureEvent.deltaUnits();
+
+    if (granularity == ScrollByPage) {
+        if (delta.width())
+            delta.setWidth(delta.width() > 0 ? 1 : -1);
+        if (delta.height())
+            delta.setHeight(delta.height() > 0 ? 1 : -1);

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

If a mousewheel is set to scroll by page, and we coalesce multiple events
together, should we scroll multiple pages? I suspect that we should.

We might want to have a test for this case.

[tdresser, 2016/01/05 16:27:32]

I didn't realize this was already the case.
Let's file a bug for this somewhere, but I don't think this is particularly high
priority.

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

I'll move it to the time the gesture is generated; that will make more sense.

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

Acknowledged.

+    }
+
     Node* node = m_scrollGestureHandlingNode.get();
     if (node) {
         LayoutObject* layoutObject = node->layoutObject();
@@ -2556,7 +2565,6 @@ WebInputEventResult EventHandler::handleGestureScrollUpdate(const PlatformGestur
                 stopNode = m_previousGestureScrolledNode.get();
 
             // First try to scroll the closest scrollable LayoutBox ancestor of |node|.
-            ScrollGranularity granularity = ScrollByPrecisePixel;
             ScrollResultOneDimensional result = scroll(ScrollLeftIgnoringWritingMode, granularity, node, &stopNode, delta.width());
             bool horizontalScroll = result.didScroll;
             if (!gestureEvent.preventPropagation())
@@ -2580,7 +2588,7 @@ WebInputEventResult EventHandler::handleGestureScrollUpdate(const PlatformGestur
         return WebInputEventResult::NotHandled;
 
     // Try to scroll the frame view.
-    ScrollResult scrollResult = m_frame->applyScrollDelta(delta, false);
+    ScrollResult scrollResult = m_frame->applyScrollDelta(granularity, delta, false);
     FloatPoint position = FloatPoint(gestureEvent.position().x(), gestureEvent.position().y());
     FloatSize velocity = FloatSize(gestureEvent.velocityX(), gestureEvent.velocityY());
     handleOverscroll(scrollResult, position, velocity);