[Impeller] turned on new blur

Author: gaaclarke

impeller/entity/contents/filters/directional_gaussian_blur_filter_contents.h

@@ -42,6 +42,9 @@ namespace impeller {
 ///   - `FilterContents::MakeGaussianBlur`
 ///   - //flutter/impeller/entity/shaders/gaussian_blur/gaussian_blur.glsl
 ///
+///\deprecated Previously 2 of these were chained to do 2D blurs, use
+///            \ref GaussianBlurFilterContents instead since it has better
+///            performance.
 class DirectionalGaussianBlurFilterContents final : public FilterContents {
  public:
   DirectionalGaussianBlurFilterContents();

impeller/entity/contents/filters/filter_contents.cc

@@ -56,38 +56,10 @@ std::shared_ptr<FilterContents> FilterContents::MakeGaussianBlur(
     Sigma sigma_y,
     BlurStyle blur_style,
     Entity::TileMode tile_mode) {
-  constexpr bool use_new_filter =
-#ifdef IMPELLER_ENABLE_NEW_GAUSSIAN_FILTER
-      true;
-#else
-      false;
-#endif
-
-  // TODO(https://github.com/flutter/flutter/issues/131580): Remove once the new
-  // blur handles all cases.
-  if (use_new_filter) {
-    auto blur =
-        std::make_shared<GaussianBlurFilterContents>(sigma_x.sigma, tile_mode);
-    blur->SetInputs({input});
-    return blur;
-  }
-  std::shared_ptr<FilterContents> x_blur = MakeDirectionalGaussianBlur(
-      /*input=*/input,
-      /*sigma=*/sigma_x,
-      /*direction=*/Point(1, 0),
-      /*blur_style=*/BlurStyle::kNormal,
-      /*tile_mode=*/tile_mode,
-      /*is_second_pass=*/false,
-      /*secondary_sigma=*/{});
-  std::shared_ptr<FilterContents> y_blur = MakeDirectionalGaussianBlur(
-      /*input=*/FilterInput::Make(x_blur),
-      /*sigma=*/sigma_y,
-      /*direction=*/Point(0, 1),
-      /*blur_style=*/blur_style,
-      /*tile_mode=*/tile_mode,
-      /*is_second_pass=*/true,
-      /*secondary_sigma=*/sigma_x);
-  return y_blur;
+  auto blur =
+      std::make_shared<GaussianBlurFilterContents>(sigma_x.sigma, tile_mode);
+  blur->SetInputs({input});
+  return blur;
 }
 
 std::shared_ptr<FilterContents> FilterContents::MakeBorderMaskBlur(