Invert DSF to map from delegated frame to layer space

cc/layers/delegated_renderer_layer_impl_unittest.cc

Index: cc/layers/delegated_renderer_layer_impl_unittest.cc
diff --git a/cc/layers/delegated_renderer_layer_impl_unittest.cc b/cc/layers/delegated_renderer_layer_impl_unittest.cc
index a2f14224aa232c162c50932d115f63a232492b67..65bdcf5e3c955c02df5ad8bb8508709045927f57 100644
--- a/cc/layers/delegated_renderer_layer_impl_unittest.cc
+++ b/cc/layers/delegated_renderer_layer_impl_unittest.cc
@@ -245,11 +245,8 @@ TEST_F(DelegatedRendererLayerImplTestSimple,
   // The DelegatedRendererLayer is at position 3,3 compared to its target, and
   // has a translation transform of 1,1. So its root RenderPass' quads should
   // all be transformed by that combined amount.
-  // The DelegatedRendererLayer has a size of 10x10, but the root delegated
-  // RenderPass has a size of 8x8, so any quads should be scaled by 10/8.
   gfx::Transform transform;
   transform.Translate(4.0, 4.0);
-  transform.Scale(10.0 / 8.0, 10.0 / 8.0);
   EXPECT_TRANSFORMATION_MATRIX_EQ(
       transform, frame.render_passes[3]->quad_list[0]->quadTransform());
 
@@ -280,12 +277,8 @@ TEST_F(DelegatedRendererLayerImplTestSimple, RenderPassTransformIsModified) {
 
   // The DelegatedRendererLayer is at position 9,9 compared to the root, so all
   // render pass' transforms to the root should be shifted by this amount.
-  // The DelegatedRendererLayer has a size of 10x10, but the root delegated
-  // RenderPass has a size of 8x8, so any render passes should be scaled by
-  // 10/8.
   gfx::Transform transform;
   transform.Translate(9.0, 9.0);
-  transform.Scale(10.0 / 8.0, 10.0 / 8.0);
 
   // The first contributing surface has a translation of 5, 6.
   gfx::Transform five_six(1, 0, 0, 1, 5, 6);
@@ -468,12 +461,9 @@ TEST_F(DelegatedRendererLayerImplTestOwnSurface,
   ASSERT_EQ(6u, frame.render_passes.size());
 
   // Because the DelegatedRendererLayer owns a RenderSurfaceImpl, its root
-  // RenderPass' quads do not need to be translated at all. However, they are
-  // scaled from the frame's size (8x8) to the layer's bounds (10x10).
-  gfx::Transform transform;
-  transform.Scale(10.0 / 8.0, 10.0 / 8.0);
+  // RenderPass' quads do not need to be translated at all.
   EXPECT_TRANSFORMATION_MATRIX_EQ(
-      transform, frame.render_passes[3]->quad_list[0]->quadTransform());
+      gfx::Transform(), frame.render_passes[3]->quad_list[0]->quadTransform());
 
   // Quads from non-root RenderPasses should not be shifted either.
   ASSERT_EQ(2u, frame.render_passes[2]->quad_list.size());
@@ -713,15 +703,10 @@ TEST_F(DelegatedRendererLayerImplTestTransform, QuadsUnclipped_NoSurface) {
   EXPECT_TRUE(root_delegated_shared_quad_state->is_clipped);
 
   gfx::Transform expected;
-  // Device scale factor is 2.
-  expected.Scale(2.0, 2.0);
   // This is the transform from the layer's space to its target.
-  // The position (20) - the width / scale (75 / 2) = 20 - 37.5 = -17.5
-  expected.Translate(-17.5, -17.5);
+  expected.Translate(-20, -20);
   expected.Scale(2.0, 2.0);
   expected.Translate(8.0, 8.0);
-  // The frame has size 100x100 but the layer's bounds are 75x75.
-  expected.Scale(75.0 / 100.0, 75.0 / 100.0);
   // This is the transform within the source frame.
   expected.Scale(1.5, 1.5);
   expected.Translate(7.0, 7.0);
@@ -761,30 +746,23 @@ TEST_F(DelegatedRendererLayerImplTestTransform, QuadsClipped_NoSurface) {
   // Since the quads have a clip_rect it should be modified by delegated
   // renderer layer's draw_transform.
   // The position of the resulting clip_rect is:
-  // (clip rect position (10) * scale to layer (75/100) + translate (8)) *
-  //     layer scale (2) + layer position (20) = 51
-  // But the layer is centered, so: 51 - (75 / 2) = 51 - 75 / 2 = 13.5
-  // The device scale is 2, so everything gets doubled, giving 27.
+  // (clip rect position (10) * inverse dsf (1/2) + translate (8)) *
+  //     layer scale (2) + layer position (20) = 46
+  // But the layer is centered, so: 46 - (75 / 2) = 46 - 75 / 2 = 8.5
+  // The device scale is 2, so everything gets doubled, giving 17.
   //
-  // The size is 35x35 scaled to fit inside the layer's bounds at 75x75 from
-  // a frame at 100x100: 35 * 2 (device scale) * 75 / 100 = 52.5. The device
-  // scale doubles this to 105.
-  EXPECT_EQ(gfx::Rect(27, 27, 105, 105).ToString(),
+  // The size is 35x35 scaled by the device scale.
+  EXPECT_EQ(gfx::Rect(17, 17, 70, 70).ToString(),
             root_delegated_shared_quad_state->clip_rect.ToString());
 
   // The quads had a clip and it should be preserved.
   EXPECT_TRUE(root_delegated_shared_quad_state->is_clipped);
 
   gfx::Transform expected;
-  // Device scale factor is 2.
-  expected.Scale(2.0, 2.0);
   // This is the transform from the layer's space to its target.
-  // The position (20) - the width / scale (75 / 2) = 20 - 37.5 = -17.5
-  expected.Translate(-17.5, -17.5);
+  expected.Translate(-20, -20);
   expected.Scale(2.0, 2.0);
   expected.Translate(8.0, 8.0);
-  // The frame has size 100x100 but the layer's bounds are 75x75.
-  expected.Scale(75.0 / 100.0, 75.0 / 100.0);
   // This is the transform within the source frame.
   expected.Scale(1.5, 1.5);
   expected.Translate(7.0, 7.0);
@@ -825,11 +803,7 @@ TEST_F(DelegatedRendererLayerImplTestTransform, QuadsUnclipped_Surface) {
 
   // When the layer owns a surface, then its position and translation are not
   // a part of its draw transform.
-  // The position of the resulting clip_rect is:
-  // (clip rect position (10) * scale to layer (75/100)) * device scale (2) = 15
-  // The size is 35x35 scaled to fit inside the layer's bounds at 75x75 from
-  // a frame at 100x100: 35 * 2 (device scale) * 75 / 100 = 52.5.
-  EXPECT_EQ(gfx::Rect(15, 15, 53, 53).ToString(),
+  EXPECT_EQ(gfx::Rect(10, 10, 35, 35).ToString(),
             root_delegated_shared_quad_state->clip_rect.ToString());
 
   // Since the layer owns a surface it doesn't need to clip its quads, so
@@ -837,10 +811,6 @@ TEST_F(DelegatedRendererLayerImplTestTransform, QuadsUnclipped_Surface) {
   EXPECT_FALSE(root_delegated_shared_quad_state->is_clipped);
 
   gfx::Transform expected;
-  // Device scale factor is 2.
-  expected.Scale(2.0, 2.0);
-  // The frame has size 100x100 but the layer's bounds are 75x75.
-  expected.Scale(75.0 / 100.0, 75.0 / 100.0);
   // This is the transform within the source frame.
   expected.Scale(1.5, 1.5);
   expected.Translate(7.0, 7.0);
@@ -880,22 +850,14 @@ TEST_F(DelegatedRendererLayerImplTestTransform, QuadsClipped_Surface) {
       &contrib_delegated_shared_quad_state);
 
   // When the layer owns a surface, then its position and translation are not
-  // a part of its draw transform.
-  // The position of the resulting clip_rect is:
-  // (clip rect position (10) * scale to layer (75/100)) * device scale (2) = 15
-  // The size is 35x35 scaled to fit inside the layer's bounds at 75x75 from
-  // a frame at 100x100: 35 * 2 (device scale) * 75 / 100 = 52.5.
-  EXPECT_EQ(gfx::Rect(15, 15, 53, 53).ToString(),
+  // a part of its draw transform. The clip_rect should be preserved.
+  EXPECT_EQ(gfx::Rect(10, 10, 35, 35).ToString(),
             root_delegated_shared_quad_state->clip_rect.ToString());
 
   // The quads had a clip and it should be preserved.
   EXPECT_TRUE(root_delegated_shared_quad_state->is_clipped);
 
   gfx::Transform expected;
-  // Device scale factor is 2.
-  expected.Scale(2.0, 2.0);
-  // The frame has size 100x100 but the layer's bounds are 75x75.
-  expected.Scale(75.0 / 100.0, 75.0 / 100.0);
   // This is the transform within the source frame.
   expected.Scale(1.5, 1.5);
   expected.Translate(7.0, 7.0);