Fixes text color of the download shelf buttons.

Fixes brave/brave-browser#20210

Chromium 97 change that caused this regression:

https://chromium.googlesource.com/chromium/src/+/4f653fca62670389f2d13571d1f64ddc34b5d88c

commit 4f653fca62670389f2d13571d1f64ddc34b5d88c
Author: Allen Bauer <kylixrd@chromium.org>
Date:   Mon Oct 18 21:02:26 2021 +0000

    Remove HasCustomColor from DownloadShelfView code.

    This also pushes the calculation of the colors into the ThemeHelper. It will slightly change the themed color calculations while keeping the colors the same for non-themed cases.

    Provided ColorProvider color mapping and calculation recipes.

    Bug: 1056953

browser/themes/theme_properties.cc

@@ -44,6 +44,8 @@ absl::optional<SkColor> MaybeGetDefaultColorForBraveLightUi(int id) {
       return kLightToolbarIcon;
     case ThemeProperties::COLOR_TOOLBAR_BUTTON_ICON_INACTIVE:
       return color_utils::AlphaBlend(kLightToolbarIcon, kLightToolbar, 0.3f);
+    case ThemeProperties::COLOR_DOWNLOAD_SHELF_BUTTON_TEXT:
+      return gfx::kBraveGrey800;  // 0x3b, 0x3e, 0x4f
     case BraveThemeProperties::COLOR_ICON_BASE:
       return SkColorSetRGB(0x49, 0x50, 0x57);
     case BraveThemeProperties::COLOR_TOGGLE_BUTTON_THUMB_ON_COLOR:
@@ -148,6 +150,8 @@ absl::optional<SkColor> MaybeGetDefaultColorForBraveDarkUi(int id) {
       return kDarkToolbarIcon;
     case ThemeProperties::COLOR_TOOLBAR_BUTTON_ICON_INACTIVE:
       return color_utils::AlphaBlend(kDarkToolbarIcon, kDarkToolbar, 0.3f);
+    case ThemeProperties::COLOR_DOWNLOAD_SHELF_BUTTON_TEXT:
+      return SK_ColorWHITE;
     case BraveThemeProperties::COLOR_ICON_BASE:
       return SkColorSetRGB(0xC2, 0xC4, 0xCF);
     case BraveThemeProperties::COLOR_TOGGLE_BUTTON_THUMB_ON_COLOR:

browser/themes/theme_properties.h

@@ -26,6 +26,7 @@ enum TestProperty {
 enum ThemeProperties {
   BRAVE_THEME_PROPERTIES_START = 10000,
   COLOR_BOOKMARK_BAR_INSTRUCTIONS_TEXT = BRAVE_THEME_PROPERTIES_START,
+  COLOR_DOWNLOAD_SHELF_BUTTON_TEXT,
   COLOR_ICON_BASE,
   COLOR_TOGGLE_BUTTON_THUMB_ON_COLOR,
   COLOR_TOGGLE_BUTTON_THUMB_OFF_COLOR,

chromium_src/chrome/browser/ui/color/chrome_color_mixer.cc

@@ -0,0 +1,31 @@
+/* Copyright (c) 2021 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "chrome/browser/ui/color/chrome_color_mixer.h"
+
+#define AddChromeColorMixer AddChromeColorMixer_ChromiumImpl
+#include "src/chrome/browser/ui/color/chrome_color_mixer.cc"
+#undef AddChromeColorMixer
+
+namespace {
+
+void AddBraveColorMixer(ui::ColorProvider* provider,
+                        const ui::ColorProviderManager::Key& key) {
+  const bool dark_mode =
+      key.color_mode == ui::ColorProviderManager::ColorMode::kDark;
+  ui::ColorMixer& mixer = provider->AddMixer();
+
+  // Download shelf colors.
+  mixer[kColorDownloadShelfButtonText] = {dark_mode ? SK_ColorWHITE
+                                                    : gfx::kBraveGrey800};
+}
+
+}  // namespace
+
+void AddChromeColorMixer(ui::ColorProvider* provider,
+                         const ui::ColorProviderManager::Key& key) {
+  AddChromeColorMixer_ChromiumImpl(provider, key);
+  AddBraveColorMixer(provider, key);
+}