Revert of Don't handle NaturalScroll in Chrome but pass it to CMT instead

ui/events/x/device_data_manager.cc

Index: ui/events/x/device_data_manager.cc
diff --git a/ui/events/x/device_data_manager.cc b/ui/events/x/device_data_manager.cc
index cac9dfda0bdbb6f93a7adf451f54070c25041984..a2e02928c4bb9288353d465c4e52f619682f06b4 100644
--- a/ui/events/x/device_data_manager.cc
+++ b/ui/events/x/device_data_manager.cc
@@ -110,7 +110,8 @@
 }
 
 DeviceDataManager::DeviceDataManager()
-    : xi_opcode_(-1),
+    : natural_scroll_enabled_(false),
+      xi_opcode_(-1),
       atom_cache_(gfx::GetXDisplay(), kCachedAtoms),
       button_map_count_(0) {
   CHECK(gfx::GetXDisplay());
@@ -174,6 +175,14 @@
 
 bool DeviceDataManager::IsXInput2Available() const {
   return xi_opcode_ != -1;
+}
+
+float DeviceDataManager::GetNaturalScrollFactor(int sourceid) const {
+  // Natural scroll is touchpad-only.
+  if (sourceid >= kMaxDeviceNum || !touchpads_[sourceid])
+    return -1.0f;
+
+  return natural_scroll_enabled_ ? 1.0f : -1.0f;
 }
 
 void DeviceDataManager::UpdateDeviceList(Display* display) {
@@ -451,17 +460,20 @@
   *y_offset_ordinal = 0;
   *finger_count = 2;
 
+  XIDeviceEvent* xiev =
+      static_cast<XIDeviceEvent*>(native_event->xcookie.data);
+  const float natural_scroll_factor = GetNaturalScrollFactor(xiev->sourceid);
   EventData data;
   GetEventRawData(*native_event, &data);
 
   if (data.find(DT_CMT_SCROLL_X) != data.end())
-    *x_offset = data[DT_CMT_SCROLL_X];
+    *x_offset = data[DT_CMT_SCROLL_X] * natural_scroll_factor;
   if (data.find(DT_CMT_SCROLL_Y) != data.end())
-    *y_offset = data[DT_CMT_SCROLL_Y];
+    *y_offset = data[DT_CMT_SCROLL_Y] * natural_scroll_factor;
   if (data.find(DT_CMT_ORDINAL_X) != data.end())
-    *x_offset_ordinal = data[DT_CMT_ORDINAL_X];
+    *x_offset_ordinal = data[DT_CMT_ORDINAL_X] * natural_scroll_factor;
   if (data.find(DT_CMT_ORDINAL_Y) != data.end())
-    *y_offset_ordinal = data[DT_CMT_ORDINAL_Y];
+    *y_offset_ordinal = data[DT_CMT_ORDINAL_Y] * natural_scroll_factor;
   if (data.find(DT_CMT_FINGER_COUNT) != data.end())
     *finger_count = static_cast<int>(data[DT_CMT_FINGER_COUNT]);
 }
@@ -476,19 +488,22 @@
   *vy_ordinal = 0;
   *is_cancel = false;
 
+  XIDeviceEvent* xiev =
+      static_cast<XIDeviceEvent*>(native_event->xcookie.data);
+  const float natural_scroll_factor = GetNaturalScrollFactor(xiev->sourceid);
   EventData data;
   GetEventRawData(*native_event, &data);
 
   if (data.find(DT_CMT_FLING_X) != data.end())
-    *vx = data[DT_CMT_FLING_X];
+    *vx = data[DT_CMT_FLING_X] * natural_scroll_factor;
   if (data.find(DT_CMT_FLING_Y) != data.end())
-    *vy = data[DT_CMT_FLING_Y];
+    *vy = data[DT_CMT_FLING_Y] * natural_scroll_factor;
   if (data.find(DT_CMT_FLING_STATE) != data.end())
     *is_cancel = !!static_cast<unsigned int>(data[DT_CMT_FLING_STATE]);
   if (data.find(DT_CMT_ORDINAL_X) != data.end())
-    *vx_ordinal = data[DT_CMT_ORDINAL_X];
+    *vx_ordinal = data[DT_CMT_ORDINAL_X] * natural_scroll_factor;
   if (data.find(DT_CMT_ORDINAL_Y) != data.end())
-    *vy_ordinal = data[DT_CMT_ORDINAL_Y];
+    *vy_ordinal = data[DT_CMT_ORDINAL_Y] * natural_scroll_factor;
 }
 
 void DeviceDataManager::GetMetricsData(const base::NativeEvent& native_event,