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

ash/wm/workspace/workspace_event_handler_unittest.cc

Index: ash/wm/workspace/workspace_event_handler_unittest.cc
diff --git a/ash/wm/workspace/workspace_event_handler_unittest.cc b/ash/wm/workspace/workspace_event_handler_unittest.cc
index 5f1e48f1bc407d3d5ed2a3bab5e64ec7fd4ce6a9..d2999e628fe46c7622c9aaa6472fa50ddb2b810b 100644
--- a/ash/wm/workspace/workspace_event_handler_unittest.cc
+++ b/ash/wm/workspace/workspace_event_handler_unittest.cc
@@ -36,7 +36,7 @@ namespace {
 void ClickButtonWithFlags(ui::test::EventGenerator* generator,
                           int button,
                           int flags) {
-  gfx::Point location = generator->current_location();
+  auto location = gfx::PointF(generator->current_location());
   ui::MouseEvent press(ui::ET_MOUSE_PRESSED, location, location,
                        ui::EventTimeForNow(), button | flags, button);
   generator->Dispatch(&press);