Migrate more functions from MathUtil to gfx::Transform

cc/layer_tree_host_common.cc

Index: cc/layer_tree_host_common.cc
diff --git a/cc/layer_tree_host_common.cc b/cc/layer_tree_host_common.cc
index feba74710b063c3c94cd154b88eb5048dfd4f225..d86cbab2095ad07edc2af6952ec62b5e73c7b553 100644
--- a/cc/layer_tree_host_common.cc
+++ b/cc/layer_tree_host_common.cc
@@ -17,6 +17,7 @@
 #include "ui/gfx/point_conversions.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/transform.h"
+#include "ui/gfx/transform_util.h"
 
 namespace cc {
 
@@ -670,7 +671,7 @@ static void calculateDrawPropertiesInternal(LayerType* layer, const gfx::Transfo
     // layerScreenSpaceTransform represents the transform between root layer's "screen space" and local content space.
     layerDrawProperties.screen_space_transform = fullHierarchyMatrix;
     if (!layer->preserves3D())
-        MathUtil::flattenTransformTo2d(layerDrawProperties.screen_space_transform);
+        gfx::FlattenTransformTo2d(layerDrawProperties.screen_space_transform);
     layerDrawProperties.screen_space_transform.PreconcatTransform(layerDrawProperties.target_space_transform);
 
     // Adjusting text AA method during animation may cause repaints, which in-turn causes jank.
@@ -824,7 +825,7 @@ static void calculateDrawPropertiesInternal(LayerType* layer, const gfx::Transfo
 
     // Flatten to 2D if the layer doesn't preserve 3D.
     if (!layer->preserves3D())
-        MathUtil::flattenTransformTo2d(sublayerMatrix);
+        gfx::FlattenTransformTo2d(sublayerMatrix);
 
     // Apply the sublayer transform at the center of the layer.
     if (!layer->sublayerTransform().IsIdentity()) {