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

cc/layers/picture_layer_impl_unittest.cc

Index: cc/layers/picture_layer_impl_unittest.cc
diff --git a/cc/layers/picture_layer_impl_unittest.cc b/cc/layers/picture_layer_impl_unittest.cc
index 78f56fd90f5333762b7190e96828047b7db79daa..f9d9eb588225d0365bbcfc329d3051b1ca84a3ce 100644
--- a/cc/layers/picture_layer_impl_unittest.cc
+++ b/cc/layers/picture_layer_impl_unittest.cc
@@ -3902,7 +3902,7 @@ TEST_F(OcclusionTrackingPictureLayerImplTest,
   gfx::Size tile_size(102, 102);
   gfx::Size layer_bounds(1000, 1000);
   gfx::Size viewport_size(500, 500);
-  gfx::Point occluding_layer_position(310, 0);
+  gfx::PointF occluding_layer_position(310.f, 0.f);
 
   host_impl_.SetViewportSize(viewport_size);
 
@@ -3961,7 +3961,7 @@ TEST_F(OcclusionTrackingPictureLayerImplTest,
   EXPECT_EQ(20, unoccluded_tile_count);
 
   // Full occlusion.
-  layer1->SetPosition(gfx::Point(0, 0));
+  layer1->SetPosition(gfx::PointF());

[vmpstr, 2015/09/29 05:04:26]

nit: I kind of weakly prefer to have explicit 0, 0 here. It's really saying
position is at 0, 0. What you have here says "position is whatever the default
point is", which just happens to be the same as (0, 0)

I feel like it's different for gfx::Rect, since when you say gfx::Rect() you
mean an empty rect, which is a reasonable default. The fact that's implemented
as 0, 0 0x0 is also an implementation detail. 

It's up to you though. This is only happening in tests, afaict, so I'm fine with
it either way.

[danakj, 2015/10/12 17:32:01]

PointF() is always 0,0 and I think that is pretty well known. There's so much
code that depends on that it's not like we could change it easily. I get what
you mean about an implementation detail but I think this is actually its API.
Point/Vector/Size/Rect are all zeros from default constructors.

 
   host_impl_.AdvanceToNextFrame(base::TimeDelta::FromMilliseconds(200));
   host_impl_.pending_tree()->UpdateDrawProperties(update_lcd_text);
@@ -3991,7 +3991,7 @@ TEST_F(OcclusionTrackingPictureLayerImplTest,
   gfx::Size tile_size(102, 102);
   gfx::Size layer_bounds(1000, 1000);
   gfx::Size viewport_size(500, 500);
-  gfx::Point occluding_layer_position(310, 0);
+  gfx::PointF occluding_layer_position(310.f, 0.f);
 
   host_impl_.SetViewportSize(viewport_size);
 
@@ -4066,7 +4066,7 @@ TEST_F(OcclusionTrackingPictureLayerImplTest,
   }
 
   // Full occlusion.
-  layer1->SetPosition(gfx::PointF(0, 0));
+  layer1->SetPosition(gfx::PointF());
 
   host_impl_.AdvanceToNextFrame(base::TimeDelta::FromMilliseconds(200));
   host_impl_.pending_tree()->UpdateDrawProperties(update_lcd_text);
@@ -4108,7 +4108,7 @@ TEST_F(OcclusionTrackingPictureLayerImplTest, OcclusionForDifferentScales) {
   gfx::Size tile_size(102, 102);
   gfx::Size layer_bounds(1000, 1000);
   gfx::Size viewport_size(500, 500);
-  gfx::Point occluding_layer_position(310, 0);
+  gfx::PointF occluding_layer_position(310.f, 0.f);
 
   scoped_refptr<FakeDisplayListRasterSource> pending_raster_source =
       FakeDisplayListRasterSource::CreateFilled(layer_bounds);
@@ -4180,7 +4180,7 @@ TEST_F(OcclusionTrackingPictureLayerImplTest, OcclusionForDifferentScales) {
 TEST_F(OcclusionTrackingPictureLayerImplTest, DifferentOcclusionOnTrees) {
   gfx::Size layer_bounds(1000, 1000);
   gfx::Size viewport_size(1000, 1000);
-  gfx::Point occluding_layer_position(310, 0);
+  gfx::PointF occluding_layer_position(310.f, 0.f);
   gfx::Rect invalidation_rect(230, 230, 102, 102);
 
   scoped_refptr<FakeDisplayListRasterSource> pending_raster_source =
@@ -4270,8 +4270,8 @@ TEST_F(OcclusionTrackingPictureLayerImplTest,
   gfx::Size tile_size(102, 102);
   gfx::Size layer_bounds(1000, 1000);
   gfx::Size viewport_size(1000, 1000);
-  gfx::Point pending_occluding_layer_position(310, 0);
-  gfx::Point active_occluding_layer_position(0, 310);
+  gfx::PointF pending_occluding_layer_position(310.f, 0.f);
+  gfx::PointF active_occluding_layer_position(0.f, 310.f);
   gfx::Rect invalidation_rect(230, 230, 152, 152);
 
   host_impl_.SetViewportSize(viewport_size);