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 TabStrip::DoLayout() {
  last_layout_size_ = size();

  StopAnimating(false);

  SwapLayoutIfNecessary();

  if (touch_layout_)
    touch_layout_->SetWidth(GetTabAreaWidth());

  UpdateIdealBounds();

  views::ViewModelUtils::SetViewBoundsToIdealBounds(tabs_);
  SetTabVisibility();

  SchedulePaint();

  bounds_animator_.StopAnimatingView(new_tab_button_);
  new_tab_button_->SetBoundsRect(new_tab_button_bounds_);
}

void TabStrip::DoLayout() {
  last_layout_size_ = size();

  StopAnimating(false);

  SwapLayoutIfNecessary();

  if (touch_layout_)
    touch_layout_->SetWidth(GetTabAreaWidth());

  UpdateIdealBounds();

  views::ViewModelUtils::SetViewBoundsToIdealBounds(tabs_);
  SetTabVisibility();

  SchedulePaint();

  bounds_animator_.StopAnimatingView(new_tab_button_);
  new_tab_button_->SetBoundsRect(new_tab_button_bounds_);
}
