Begin removing deprecated (and now, unused) ImageFilter code paths

This CL focuses on removing the Proxy objects but takes some other stuff with it.

BUG=skia:4965
TBR=reed@google.com

GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1896383003

Review URL: https://codereview.chromium.org/1896383003
diff --git a/tests/ImageFilterCacheTest.cpp b/tests/ImageFilterCacheTest.cpp
index 688069e..40c805a 100644
--- a/tests/ImageFilterCacheTest.cpp
+++ b/tests/ImageFilterCacheTest.cpp
@@ -138,11 +138,11 @@
 
     const SkIRect& full = SkIRect::MakeWH(kFullSize, kFullSize);
 
-    sk_sp<SkSpecialImage> fullImg(SkSpecialImage::MakeFromRaster(nullptr, full, srcBM));
+    sk_sp<SkSpecialImage> fullImg(SkSpecialImage::MakeFromRaster(full, srcBM));
 
     const SkIRect& subset = SkIRect::MakeXYWH(kPad, kPad, kSmallerSize, kSmallerSize);
 
-    sk_sp<SkSpecialImage> subsetImg(SkSpecialImage::MakeFromRaster(nullptr, subset, srcBM));
+    sk_sp<SkSpecialImage> subsetImg(SkSpecialImage::MakeFromRaster(subset, srcBM));
 
     test_find_existing(reporter, fullImg, subsetImg);
     test_dont_find_if_diff_key(reporter, fullImg, subsetImg);
@@ -155,11 +155,11 @@
 static void test_image_backed(skiatest::Reporter* reporter, const sk_sp<SkImage>& srcImage) {
     const SkIRect& full = SkIRect::MakeWH(kFullSize, kFullSize);
 
-    sk_sp<SkSpecialImage> fullImg(SkSpecialImage::MakeFromImage(nullptr, full, srcImage));
+    sk_sp<SkSpecialImage> fullImg(SkSpecialImage::MakeFromImage(full, srcImage));
 
     const SkIRect& subset = SkIRect::MakeXYWH(kPad, kPad, kSmallerSize, kSmallerSize);
 
-    sk_sp<SkSpecialImage> subsetImg(SkSpecialImage::MakeFromImage(nullptr, subset, srcImage));
+    sk_sp<SkSpecialImage> subsetImg(SkSpecialImage::MakeFromImage(subset, srcImage));
 
     test_find_existing(reporter, fullImg, subsetImg);
     test_dont_find_if_diff_key(reporter, fullImg, subsetImg);
@@ -220,13 +220,13 @@
 
     const SkIRect& full = SkIRect::MakeWH(kFullSize, kFullSize);
 
-    sk_sp<SkSpecialImage> fullImg(SkSpecialImage::MakeFromGpu(nullptr, full,
+    sk_sp<SkSpecialImage> fullImg(SkSpecialImage::MakeFromGpu(full,
                                                               kNeedNewImageUniqueID_SpecialImage,
                                                               srcTexture));
 
     const SkIRect& subset = SkIRect::MakeXYWH(kPad, kPad, kSmallerSize, kSmallerSize);
 
-    sk_sp<SkSpecialImage> subsetImg(SkSpecialImage::MakeFromGpu(nullptr, subset,
+    sk_sp<SkSpecialImage> subsetImg(SkSpecialImage::MakeFromGpu(subset,
                                                                 kNeedNewImageUniqueID_SpecialImage,
                                                                 srcTexture));