Tabstrip animations respect gfx::Animation::ShouldRenderRichAnimations.

This allows tabstrip animations to be disabled during tests and with
various operating system settings.

Bug: 8944
Change-Id: I56d7edb7fd3c05f98e2ada0b3e14efaef5cf9ae4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1812131Reviewed-by: Charlene Yan <cyan@chromium.org>
Commit-Queue: Charlene Yan <cyan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#697836}

chrome/browser/ui/views/tabs/tab_strip_layout_helper.cc

@@ -501,6 +501,11 @@ TabStripLayoutHelper::GetCurrentTabWidthConstraints() const {
 void TabStripLayoutHelper::AnimateSlot(int slots_index,
                                        TabAnimationState target_state) {
   slots_[slots_index].animation->AnimateTo(target_state);
+  if (!gfx::Animation::ShouldRenderRichAnimation()) {
+    slots_[slots_index].animation->CompleteAnimation();
+    on_animation_progressed_.Run();
+    return;
+  }
   if (!animation_timer_.IsRunning()) {
     animation_timer_.Start(FROM_HERE, kTickInterval, this,
                            &TabStripLayoutHelper::TickAnimations);