Update filter blending to match spec draft.

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 7f439b9f15c102469eb9ee2b1f41067baeec7b19..329601fd7260aabc89f5b693203ce5071d09bb11 100644
--- a/cc/output/filter_operations_unittest.cc
+++ b/cc/output/filter_operations_unittest.cc
@@ -644,8 +644,7 @@ TEST(FilterOperationsTest, BlendEmptySequences) {
   EXPECT_EQ(blended, empty);
 }
 
-// Tests blending non-empty sequences that either have different lengths or
-// have non-matching operations.
+// Tests blending non-empty sequences that have non-matching operations.
 TEST(FilterOperationsTest, BlendNonMatchingSequences) {
   FilterOperations from;
   FilterOperations to;
@@ -653,6 +652,7 @@ TEST(FilterOperationsTest, BlendNonMatchingSequences) {
   from.Append(FilterOperation::CreateSaturateFilter(3.f));
   from.Append(FilterOperation::CreateBlurFilter(2.f));
   to.Append(FilterOperation::CreateSaturateFilter(4.f));
+  to.Append(FilterOperation::CreateHueRotateFilter(0.5f));
 
   FilterOperations blended = to.Blend(from, -0.75);
   EXPECT_EQ(to, blended);
@@ -660,8 +660,37 @@ TEST(FilterOperationsTest, BlendNonMatchingSequences) {
   EXPECT_EQ(to, blended);
   blended = to.Blend(from, 1.5);
   EXPECT_EQ(to, blended);
+}
 
-  to.Append(FilterOperation::CreateHueRotateFilter(0.5f));
+// Tests blending non-empty sequences of different sizes.
+TEST(FilterOperationsTest, BlendRaggedSequences) {
+  FilterOperations from;
+  FilterOperations to;
+
+  from.Append(FilterOperation::CreateSaturateFilter(3.f));
+  from.Append(FilterOperation::CreateBlurFilter(2.f));
+  to.Append(FilterOperation::CreateSaturateFilter(4.f));
+
+  FilterOperations blended = to.Blend(from, -0.75);
+  FilterOperations expected;
+  expected.Append(FilterOperation::CreateSaturateFilter(2.25f));
+  expected.Append(FilterOperation::CreateBlurFilter(3.5f));
+  EXPECT_EQ(expected, blended);
+
+  blended = to.Blend(from, 0.75);
+  expected.Clear();
+  expected.Append(FilterOperation::CreateSaturateFilter(3.75f));
+  expected.Append(FilterOperation::CreateBlurFilter(0.5f));
+  EXPECT_EQ(expected, blended);
+
+  blended = to.Blend(from, 1.5);
+  expected.Clear();
+  expected.Append(FilterOperation::CreateSaturateFilter(4.5f));
+  expected.Append(FilterOperation::CreateBlurFilter(0.f));
+  EXPECT_EQ(expected, blended);
+
+  from.Append(FilterOperation::CreateOpacityFilter(1.f));
+  to.Append(FilterOperation::CreateOpacityFilter(1.f));
   blended = to.Blend(from, -0.75);
   EXPECT_EQ(to, blended);
   blended = to.Blend(from, 0.75);