Rebaseline two backdrop filter cc_unittests for SkiaRenderer Dawn

Bug: 1139118
Change-Id: I93ac21edbeb2317f677770b32dfe482715e44c18
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2481355Reviewed-by: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Reviewed-by: Jonathan Backer <backer@chromium.org>
Commit-Queue: Brian Salomon <bsalomon@google.com>
Cr-Commit-Position: refs/heads/master@{#818582}

cc/trees/layer_tree_host_pixeltest_filters.cc

@@ -175,11 +175,11 @@ TEST_P(LayerTreeHostFiltersPixelTest, BackdropFilterBlurRadius) {
   float percentage_pixels_large_error = 1.09f;  // 436px / (200*200)
   float percentage_pixels_small_error = 0.0f;
   float average_error_allowed_in_bad_pixels = 1.f;
-  int large_error_allowed = 1;
+  int large_error_allowed = 2;
   int small_error_allowed = 0;
-  // Windows using Dawn D3D12 has 2982 pixels off by 1.
+  // Windows using Dawn D3D12 has 4044 pixels off by max of 2.
   if (use_d3d12())
-    percentage_pixels_large_error = 1.864f;  // 2982px / (400*400)
+    percentage_pixels_large_error = 2.5275f;  // 4044px / (400*400)
   pixel_comparator_.reset(new FuzzyPixelComparator(
       true,  // discard_alpha
       percentage_pixels_large_error, percentage_pixels_small_error,

testing/buildbot/filters/gpu.skiarenderer_dawn_cc_unittests.filter

-# crbug.com/1139118: new blur algorithm
--All/LayerTreeHostFiltersPixelTest.BackdropFilterBlurRadius/SkiaDawn
--All/LayerTreeHostFiltersPixelTest.BackdropFilterRotated/SkiaDawn