Make WebGestureEvent coords and device private

This CL changes WebGestureEvent coordinates to private and float
to match other Web* class e.g. WebMouseEvent.

x, y -> position_in_widget_
global_x, global_y -> position_in_screen_

This also changes source_device to private source_device_.
Add set source_device_ in constructor, and add setter and getter.
SetSourceDevice will be eliminated in future CL (should be set in constructor)

Bug: 817104
Cq-Include-Trybots: luci.chromium.try:linux_optional_gpu_tests_rel;master.tryserver.blink:linux_trusty_blink_rel;master.tryserver.chromium.android:android_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_layout_tests_slimming_paint_v2;master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.linux:linux_vr;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel
Change-Id: Iea504fdf4ef1c66610e221343031a6b0f38e7a04
Reviewed-on: https://chromium-review.googlesource.com/953655
Reviewed-by: Avi Drissman <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Kentaro Hara <[email protected]>
Reviewed-by: David Bokan <[email protected]>
Reviewed-by: Timothy Dresser <[email protected]>
Cr-Commit-Position: refs/heads/master@{#544619}
diff --git a/content/renderer/render_widget.cc b/content/renderer/render_widget.cc
index 4bc49d3..04ef8e7 100644
--- a/content/renderer/render_widget.cc
+++ b/content/renderer/render_widget.cc
@@ -1321,7 +1321,7 @@
   possible_drag_event_info_.event_source =
       ui::DragDropTypes::DRAG_EVENT_SOURCE_TOUCH;
   possible_drag_event_info_.event_location =
-      gfx::Point(event.global_x, event.global_y);
+      gfx::ToFlooredPoint(event.PositionInScreen());
 
   return false;
 }