color: Clarify default behaviors

ui/gfx/color_space_unittest.cc

 // Copyright 2017 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <cmath>
 
 #include "base/logging.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/color_space.h"
 
@@ skipping 61 matching lines @@
     SkMatrix44 range_adjust_inv;
     range_adjust.invert(&range_adjust_inv);
 
     for (size_t j = 0; j < kNumTestRGBs; ++j) {
       SkVector4 yuv = range_adjust_inv * transfer * test_rgbs[j];
       EXPECT_LT(Diff(yuv, expected_yuvs[i][j]), kEpsilon);
     }
   }
 }
 
+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