Paint tab groups with the group color.

* The background of TabGroupHeader now uses the group color.
* The backgrounds of tabs in the group are tinted with the group color.

This treatment, along with the colors chosen, are intended to be
a placeholder.

Bug: 905491
Change-Id: Ic808548f8eba23064606e7fb8c9bba281d0d117f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610504
Commit-Queue: Bret Sepulveda <bsep@chromium.org>
Reviewed-by: Taylor Bergquist <tbergquist@chromium.org>
Cr-Commit-Position: refs/heads/master@{#660498}
void Tab::UpdateForegroundColors() {
  TabStyle::TabColors colors = tab_style_->CalculateColors();

  icon_->SetBackgroundColor(colors.background_color);
  title_->SetEnabledColor(colors.title_color);

  close_button_->SetIconColors(
      colors.button_icon_idle_color, colors.button_icon_hovered_color,
      colors.button_icon_hovered_color, colors.button_background_hovered_color,
      colors.button_background_pressed_color);

  if (button_color_ != colors.button_icon_idle_color) {
    button_color_ = colors.button_icon_idle_color;
    alert_indicator_->OnParentTabButtonColorChanged();
  }

  SchedulePaint();
}

void Tab::UpdateForegroundColors() {
  TabStyle::TabColors colors = tab_style_->CalculateColors();

  icon_->SetBackgroundColor(colors.background_color);
  title_->SetEnabledColor(colors.title_color);

  close_button_->SetIconColors(
      colors.button_icon_idle_color, colors.button_icon_hovered_color,
      colors.button_icon_hovered_color, colors.button_background_hovered_color,
      colors.button_background_pressed_color);

  if (button_color_ != colors.button_icon_idle_color) {
    button_color_ = colors.button_icon_idle_color;
    alert_indicator_->OnParentTabButtonColorChanged();
  }

  SchedulePaint();
}
