color: Clarify default behaviors

ui/gfx/color_transform_unittest.cc

 // Copyright (c) 2016 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 "base/logging.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/color_space.h"
 #include "ui/gfx/color_transform.h"
 #include "ui/gfx/icc_profile.h"
 #include "ui/gfx/test/icc_profiles.h"
@@ skipping 81 matching lines @@
   ICCProfile srgb_icc_profile = ICCProfileForTestingSRGB();
   ColorSpace srgb_fromicc = srgb_icc_profile.GetColorSpace();
   ColorSpace srgb_default = gfx::ColorSpace::CreateSRGB();
   ColorSpace xyzd50 = gfx::ColorSpace::CreateXYZD50();
 
   value_fromicc = value_default = ColorTransform::TriStim(0.1, 0.5, 0.9);
 
   std::unique_ptr<ColorTransform> toxyzd50_fromicc(
       ColorTransform::NewColorTransform(
           srgb_fromicc, xyzd50, ColorTransform::Intent::INTENT_ABSOLUTE));
-  // This will have 1 step, namely, the QCMS transform.
-  EXPECT_EQ(toxyzd50_fromicc->NumberOfStepsForTesting(), 1u);
+  // This will be converted to a transfer function and then linear transform.
+  EXPECT_EQ(toxyzd50_fromicc->NumberOfStepsForTesting(), 2u);
   toxyzd50_fromicc->Transform(&value_fromicc, 1);
 
   std::unique_ptr<ColorTransform> toxyzd50_default(
       ColorTransform::NewColorTransform(
           srgb_default, xyzd50, ColorTransform::Intent::INTENT_ABSOLUTE));
   // This will have a transfer function and then linear transform.
   EXPECT_EQ(toxyzd50_default->NumberOfStepsForTesting(), 2u);
   toxyzd50_default->Transform(&value_default, 1);
 
   EXPECT_NEAR(value_fromicc.x(), value_default.x(), kEpsilon);
@@ skipping 79 matching lines @@
   EXPECT_NEAR(tmp.y(), 0.0f, kEpsilon);
   EXPECT_NEAR(tmp.z(), 1.0f, kEpsilon);
 }
 
 TEST(SimpleColorSpace, UnknownToSRGB) {
   ColorSpace unknown;
   ColorSpace sRGB = ColorSpace::CreateSRGB();
   std::unique_ptr<ColorTransform> t(ColorTransform::NewColorTransform(
       unknown, sRGB, ColorTransform::Intent::INTENT_PERCEPTUAL));
 
-  ColorTransform::TriStim tmp(16.0f / 255.0f, 0.5f, 0.5f);
+  EXPECT_EQ(t->NumberOfStepsForTesting(), 0u);
+
+  ColorTransform::TriStim input;
+  ColorTransform::TriStim tmp;
+  input = ColorTransform::TriStim(16.0f / 255.0f, 0.5f, 0.5f);
+  tmp = input;
   t->Transform(&tmp, 1);
-  EXPECT_NEAR(tmp.x(), 0.0f, 0.001f);
-  EXPECT_NEAR(tmp.y(), 0.0f, 0.001f);
-  EXPECT_NEAR(tmp.z(), 0.0f, 0.001f);
+  EXPECT_NEAR(tmp.x(), input.x(), 0.001f);
+  EXPECT_NEAR(tmp.y(), input.y(), 0.001f);
+  EXPECT_NEAR(tmp.z(), input.z(), 0.001f);
 
-  tmp = ColorTransform::TriStim(235.0f / 255.0f, 0.5f, 0.5f);
+  input = ColorTransform::TriStim(235.0f / 255.0f, 0.5f, 0.5f);
+  tmp = input;
   t->Transform(&tmp, 1);
-  EXPECT_NEAR(tmp.x(), 1.0f, 0.001f);
-  EXPECT_NEAR(tmp.y(), 1.0f, 0.001f);
-  EXPECT_NEAR(tmp.z(), 1.0f, 0.001f);
+  EXPECT_NEAR(tmp.x(), input.x(), 0.001f);
+  EXPECT_NEAR(tmp.y(), input.y(), 0.001f);
+  EXPECT_NEAR(tmp.z(), input.z(), 0.001f);
 
   // Test a blue color
-  tmp = ColorTransform::TriStim(128.0f / 255.0f, 240.0f / 255.0f, 0.5f);
+  input = ColorTransform::TriStim(128.0f / 255.0f, 240.0f / 255.0f, 0.5f);
+  tmp = input;
   t->Transform(&tmp, 1);
-  EXPECT_GT(tmp.z(), tmp.x());
-  EXPECT_GT(tmp.z(), tmp.y());
+  EXPECT_NEAR(tmp.x(), input.x(), 0.001f);
+  EXPECT_NEAR(tmp.y(), input.y(), 0.001f);
+  EXPECT_NEAR(tmp.z(), input.z(), 0.001f);
 }
 
 class TransferTest : public testing::TestWithParam<ColorSpace::TransferID> {};
 
 TEST_P(TransferTest, basicTest) {
   gfx::ColorSpace space_with_transfer(ColorSpace::PrimaryID::BT709, GetParam(),
                                       ColorSpace::MatrixID::RGB,
                                       ColorSpace::RangeID::FULL);
   gfx::ColorSpace space_linear(
       ColorSpace::PrimaryID::BT709, ColorSpace::TransferID::LINEAR,
@@ skipping 90 matching lines @@
 
 INSTANTIATE_TEST_CASE_P(
     C,
     ColorSpaceTest,
     testing::Combine(testing::ValuesIn(all_primaries),
                      testing::Values(ColorSpace::TransferID::BT709),
                      testing::ValuesIn(all_matrices),
                      testing::ValuesIn(all_ranges),
                      testing::ValuesIn(intents)));
 }  // namespace