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

cc/test/layer_tree_json_parser_unittest.cc

Index: cc/test/layer_tree_json_parser_unittest.cc
diff --git a/cc/test/layer_tree_json_parser_unittest.cc b/cc/test/layer_tree_json_parser_unittest.cc
index 4f97945e253a6bc8538174ffb5af27cadc182c1a..f1388c0f273d3feae2590741eb17615d03b698c6 100644
--- a/cc/test/layer_tree_json_parser_unittest.cc
+++ b/cc/test/layer_tree_json_parser_unittest.cc
@@ -78,7 +78,7 @@ TEST_F(LayerTreeJsonParserSanityCheck, Basic) {
   parent->SetBounds(gfx::Size(50, 50));
   child->SetBounds(gfx::Size(40, 40));
 
-  parent->SetPosition(gfx::Point(25, 25));
+  parent->SetPosition(gfx::PointF(25.f, 25.f));
 
   child->SetHaveWheelEventHandlers(true);
   child->SetHaveScrollEventHandlers(true);