Scale the ALPHA_THRESHOLD filter's region based on the device scale factor.

cc/output/filter_operations_unittest.cc

Index: cc/output/filter_operations_unittest.cc
diff --git a/cc/output/filter_operations_unittest.cc b/cc/output/filter_operations_unittest.cc
index e97379cbd2a6c38b53cb97bb7802997ffd700833..4bbf3dd7442a85be4052e232b26bdda188ab2072 100644
--- a/cc/output/filter_operations_unittest.cc
+++ b/cc/output/filter_operations_unittest.cc
@@ -140,6 +140,35 @@ TEST(FilterOperationsTest, SaveAndRestore) {
   SAVE_RESTORE_AMOUNT_INSET(Zoom, ZOOM, 0.5f, 32);
 }
 
+TEST(FilterOperationsTest, SaveAndRestoreAlphaThreshold) {
+  SkRegion region(SkIRect::MakeLTRB(20, 10, 300, 200));
+  float inner = 0.6f;
+  float outer = 0.3f;
+
+  FilterOperation op =
+      FilterOperation::CreateAlphaThresholdFilter(region, inner, outer);
+  EXPECT_EQ(FilterOperation::ALPHA_THRESHOLD, op.type());
+  EXPECT_EQ(region, op.region());
+  EXPECT_EQ(inner, op.amount());
+  EXPECT_EQ(outer, op.outer_threshold());
+
+  FilterOperation op2 = FilterOperation::CreateEmptyFilter();
+  op2.set_type(FilterOperation::ALPHA_THRESHOLD);
+
+  EXPECT_NE(region, op2.region());
+  EXPECT_NE(inner, op2.amount());
+  EXPECT_NE(outer, op2.outer_threshold());
+
+  op2.set_region(region);
+  op2.set_amount(inner);
+  op2.set_outer_threshold(outer);
+
+  EXPECT_EQ(FilterOperation::ALPHA_THRESHOLD, op2.type());
+  EXPECT_EQ(region, op2.region());
+  EXPECT_EQ(inner, op2.amount());
+  EXPECT_EQ(outer, op2.outer_threshold());
+}
+
 TEST(FilterOperationsTest, BlendGrayscaleFilters) {
   FilterOperation from = FilterOperation::CreateGrayscaleFilter(0.25f);
   FilterOperation to = FilterOperation::CreateGrayscaleFilter(0.75f);
@@ -543,6 +572,35 @@ TEST(FilterOperationsTest, BlendReferenceWithNull) {
   EXPECT_EQ(filter, blended);
 }
 
+TEST(FilterOperationsTest, BlendAlphaThresholdFilters) {
+  SkRegion start_region(SkIRect::MakeLTRB(15, 5, 200, 100));
+  SkRegion end_region(SkIRect::MakeLTRB(20, 10, 300, 200));
+
+  FilterOperation from =
+      FilterOperation::CreateAlphaThresholdFilter(start_region, 0.25f, 0.25f);
+  FilterOperation to =
+      FilterOperation::CreateAlphaThresholdFilter(end_region, 0.75f, 0.75f);
+
+  FilterOperation blended = FilterOperation::Blend(&from, &to, -0.75);
+  FilterOperation expected =
+      FilterOperation::CreateAlphaThresholdFilter(start_region, 0.f, 0.f);
+  EXPECT_EQ(expected, blended);
+
+  blended = FilterOperation::Blend(&from, &to, 0.25);
+  expected =
+      FilterOperation::CreateAlphaThresholdFilter(start_region, 0.375f, 0.375f);
+  EXPECT_EQ(expected, blended);
+
+  blended = FilterOperation::Blend(&from, &to, 0.75);
+  expected =
+      FilterOperation::CreateAlphaThresholdFilter(end_region, 0.625f, 0.625f);
+  EXPECT_EQ(expected, blended);
+
+  blended = FilterOperation::Blend(&from, &to, 1.8);
+  expected = FilterOperation::CreateAlphaThresholdFilter(end_region, 1.f, 1.f);
+  EXPECT_EQ(expected, blended);
+}
+
 // Tests blending non-empty sequences that have the same length and matching
 // operations.
 TEST(FilterOperationsTest, BlendMatchingSequences) {