color_utils cleanup:

components/favicon_base/fallback_icon_style.cc

 // Copyright 2015 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 "components/favicon_base/fallback_icon_style.h"
 
 #include <algorithm>
 
 #include "ui/gfx/color_analysis.h"
 #include "ui/gfx/color_utils.h"
 
 namespace favicon_base {
 
 namespace {
 
-// Luminance threshold for background color determine whether to use dark or
-// light text color.
-const int kDarkTextLuminanceThreshold = 190;
+// Luma threshold for background color determine whether to use dark or light
+// text color.
+const uint8_t kDarkTextLumaThreshold = 190;
 
-// The maximum luminance of the background color to ensure light text is
+// The maximum lightness of the background color to ensure light text is
 // readable.
-const double kMaxBackgroundColorLuminance = 0.67;
-const double kMinBackgroundColorLuminance = 0.15;
+const double kMaxBackgroundColorLightness = 0.67;
+const double kMinBackgroundColorLightness = 0.15;
 
 // Default values for FallbackIconStyle.
 const SkColor kDefaultBackgroundColor = SkColorSetRGB(0x78, 0x78, 0x78);
 const SkColor kDefaultTextColorDark = SK_ColorBLACK;
 const SkColor kDefaultTextColorLight = SK_ColorWHITE;
 const double kDefaultFontSizeRatio = 0.44;
 const double kDefaultRoundness = 0;  // Square. Round corners are applied
                                      // externally (Javascript or Java).
 
 }  // namespace
@@ skipping 10 matching lines @@
 
 bool FallbackIconStyle::operator==(const FallbackIconStyle& other) const {
   return background_color == other.background_color &&
       text_color == other.text_color &&
       font_size_ratio == other.font_size_ratio &&
       roundness == other.roundness;
 }
 
 void MatchFallbackIconTextColorAgainstBackgroundColor(
     FallbackIconStyle* style) {
-  int luminance = color_utils::GetLuminanceForColor(style->background_color);
-  style->text_color = (luminance >= kDarkTextLuminanceThreshold ?
-      kDefaultTextColorDark : kDefaultTextColorLight);
+  const uint8_t luma = color_utils::Luma(style->background_color);
+  style->text_color = (luma >= kDarkTextLumaThreshold) ?
+      kDefaultTextColorDark : kDefaultTextColorLight;
 }
 
 bool ValidateFallbackIconStyle(const FallbackIconStyle& style) {
   return style.font_size_ratio >= 0.0 && style.font_size_ratio <= 1.0 &&
       style.roundness >= 0.0 && style.roundness <= 1.0;
 }
 
 void SetDominantColorAsBackground(
     const scoped_refptr<base::RefCountedMemory>& bitmap_data,
     FallbackIconStyle* style) {
-  // Try to ensure color's luminance isn't too large so that light text is
+  // Try to ensure color's lightness isn't too large so that light text is
   // visible. Set an upper bound for the dominant color.
-  const color_utils::HSL lower_bound{-1.0, -1.0, kMinBackgroundColorLuminance};
-  const color_utils::HSL upper_bound{-1.0, -1.0, kMaxBackgroundColorLuminance};
+  const color_utils::HSL lower_bound{-1.0, -1.0, kMinBackgroundColorLightness};
+  const color_utils::HSL upper_bound{-1.0, -1.0, kMaxBackgroundColorLightness};
   color_utils::GridSampler sampler;
   SkColor dominant_color = color_utils::CalculateKMeanColorOfPNG(
       bitmap_data, lower_bound, upper_bound, &sampler);
   // |CalculateKMeanColorOfPNG| will try to return a color that lies within the
   // specified bounds if one exists in the image. If there's no such color, it
   // will return the dominant color which may be lighter than our upper bound.
-  // Clamp luminance down to a reasonable maximum value so text is readable.
+  // Clamp lightness down to a reasonable maximum value so text is readable.
   color_utils::HSL color_hsl;
   color_utils::SkColorToHSL(dominant_color, &color_hsl);
-  color_hsl.l = std::min(color_hsl.l, kMaxBackgroundColorLuminance);
+  color_hsl.l = std::min(color_hsl.l, kMaxBackgroundColorLightness);
   style->background_color =
       color_utils::HSLToSkColor(color_hsl, SK_AlphaOPAQUE);
 }
 
 }  // namespace favicon_base