dark_mode: Keep enabled color for brightness icon.

Bug: 1145363
Change-Id: Ia1d5a051aa2da436855b5891923a8b091d2039a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2537592Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#827355}

ash/system/brightness/unified_brightness_view.cc

@@ -7,7 +7,9 @@
 #include "ash/resources/vector_icons/vector_icons.h"
 #include "ash/shell.h"
 #include "ash/strings/grit/ash_strings.h"
+#include "ash/style/ash_color_provider.h"
 #include "ash/system/brightness/unified_brightness_slider_controller.h"
+#include "ui/gfx/paint_vector_icon.h"
 
 namespace ash {
 
@@ -37,4 +39,17 @@ const char* UnifiedBrightnessView::GetClassName() const {
   return "UnifiedBrightnessView";
 }
 
+void UnifiedBrightnessView::OnThemeChanged() {
+  UnifiedSliderView::OnThemeChanged();
+
+  // Override the color for the icon. Since the button is set to disabled but
+  // wants to keep the color for an enabled icon.
+  button()->SetImage(
+      views::Button::STATE_DISABLED,
+      gfx::CreateVectorIcon(
+          kUnifiedMenuBrightnessIcon,
+          AshColorProvider::Get()->GetContentLayerColor(
+              AshColorProvider::ContentLayerType::kButtonIconColor)));
+}
+
 }  // namespace ash

ash/system/brightness/unified_brightness_view.h

@@ -26,6 +26,7 @@ class UnifiedBrightnessView : public UnifiedSliderView,
 
   // views::View:
   const char* GetClassName() const override;
+  void OnThemeChanged() override;
 
  private:
   UnifiedSystemTrayModel* const model_;