gfx: Make conversions from gfx::Point to PointF explicit.

ui/aura/window_tree_host.cc

Index: ui/aura/window_tree_host.cc
diff --git a/ui/aura/window_tree_host.cc b/ui/aura/window_tree_host.cc
index 1e0c0e06fe02a85db0a646cb94eee172213ce066..5c9f25cd549d024484d4ae4a3f4b102f27e3a0d3 100644
--- a/ui/aura/window_tree_host.cc
+++ b/ui/aura/window_tree_host.cc
@@ -122,13 +122,13 @@ void WindowTreeHost::ConvertPointFromNativeScreen(gfx::Point* point) const {
 }
 
 void WindowTreeHost::ConvertPointToHost(gfx::Point* point) const {
-  gfx::Point3F point_3f(*point);
+  auto point_3f = gfx::Point3F(gfx::PointF(*point));
   GetRootTransform().TransformPoint(&point_3f);
   *point = gfx::ToFlooredPoint(point_3f.AsPointF());
 }
 
 void WindowTreeHost::ConvertPointFromHost(gfx::Point* point) const {
-  gfx::Point3F point_3f(*point);
+  auto point_3f = gfx::Point3F(gfx::PointF(*point));
   GetInverseRootTransform().TransformPoint(&point_3f);
   *point = gfx::ToFlooredPoint(point_3f.AsPointF());
 }