color: Clarify default behaviors

ui/gfx/color_space_unittest.cc

Index: ui/gfx/color_space_unittest.cc
diff --git a/ui/gfx/color_space_unittest.cc b/ui/gfx/color_space_unittest.cc
index 1c652fa535ab7aea6ccd27934cc111ee4f348964..9e1dc77d0d97bf99a55e1269f084feb46de674c8 100644
--- a/ui/gfx/color_space_unittest.cc
+++ b/ui/gfx/color_space_unittest.cc
@@ -79,5 +79,50 @@ TEST(ColorSpace, RGBToYUV) {
   }
 }
 
+TEST(ColorSpace, VideoFormats) {
+  int primary_min = 0;
+  int primary_default = 1;
+  int primary_max = 12;
+
+  int transfer_min = 0;
+  int transfer_default = 1;
+  int transfer_max = 18;
+
+  int matrix_min = 0;
+  int matrix_default = 1;
+  int matrix_max = 11;
+
+  for (int i = -10; i < 30; ++i) {
+    int primary = primary_min + i;
+    int transfer = transfer_min + i;
+    int matrix = primary_min + i;
+    gfx::ColorSpace space = gfx::ColorSpace::CreateVideo(
+        primary, transfer, matrix, gfx::ColorSpace::RangeID::FULL);
+
+    int out_primary = -1;
+    int out_transfer = -1;
+    int out_matrix = -1;
+    bool full_range = false;
+    space.GetVideoParameters(&out_primary, &out_transfer, &out_matrix,
+                             &full_range);
+    if (primary >= primary_min && primary <= primary_max)
+      EXPECT_EQ(primary, out_primary);
+    else
+      EXPECT_EQ(primary_default, out_primary);
+
+    if (transfer >= transfer_min && transfer <= transfer_max)
+      EXPECT_EQ(transfer, out_transfer);
+    else
+      EXPECT_EQ(transfer_default, out_transfer);
+
+    if (matrix >= matrix_min && matrix <= matrix_max)
+      EXPECT_EQ(matrix, out_matrix);
+    else
+      EXPECT_EQ(matrix_default, out_matrix);
+
+    EXPECT_TRUE(full_range);
+  }
+}
+
 }  // namespace
 }  // namespace gfx