Prevent one frame of text pop when sliding hover cards.

Visibility change on animation start resulted in alpha overlay not
painting until next animation frame, resulting in the underlying text
(representing the new title and domain) showing through at 100% opacity.

Now the overlay always draws but possibly at zero opacity, avoiding the
issue. The text is still cleared when the card reaches its destination
so we don't incur the overhead of laying out the text.

Change-Id: Id1e0587874f7e91dad4efdf0fd31f2ac23860ceb
Bug: 1023956
Fixes: 1023956
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1910681
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Auto-Submit: Dana Fried <dfried@chromium.org>
Cr-Commit-Position: refs/heads/master@{#714817}

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

@@ -261,8 +261,8 @@ class TabHoverCardBubbleView::WidgetSlideAnimationDelegate
       if (desired_anchor_view_)
         bubble_delegate_->SetAnchorView(desired_anchor_view_);
     }
-    bubble_delegate_->UpdateTextFade(value);
     bubble_delegate_->GetWidget()->SetBounds(current_bubble_bounds_);
+    bubble_delegate_->UpdateTextFade(value);
   }
 
   void AnimationEnded(const gfx::Animation* animation) override {
@@ -300,16 +300,12 @@ class TabHoverCardBubbleView::FadeLabel : public views::Label {
   // FadeLabel is designed to mask new text with the old and then fade away, the
   // higher the percentage the less opaque the label.
   void SetFade(double percent) {
-    if (percent >= 1.0) {
-      SetVisible(false);
-      return;
-    }
-
+    if (percent >= 1.0)
+      SetText(base::string16());
     const SkAlpha alpha = base::saturated_cast<SkAlpha>(
         std::numeric_limits<SkAlpha>::max() * (1.0 - percent));
     SetBackgroundColor(SkColorSetA(GetBackgroundColor(), alpha));
     SetEnabledColor(SkColorSetA(GetEnabledColor(), alpha));
-    SetVisible(true);
   }
 
  protected:
@@ -552,11 +548,6 @@ void TabHoverCardBubbleView::UpdateAndShow(Tab* tab) {
 
   if (widget_->IsVisible() && !disable_animations_for_testing_) {
     slide_animation_delegate_->AnimateToAnchorView(tab);
-    // Reset the text fade, but only if we're not already animating. If we are,
-    // it will be less disruptive to just continue the animation with the new
-    // text.
-    if (!slide_animation_delegate_->is_animating())
-      UpdateTextFade(0.0);
   } else {
     if (!anchor_view_set)
       SetAnchorView(tab);
@@ -721,6 +712,7 @@ void TabHoverCardBubbleView::UpdateCardContent(const Tab* tab) {
             url_formatter::kFormatUrlTrimAfterHost,
         net::UnescapeRule::NORMAL, nullptr, nullptr, nullptr);
   }
+  UpdateTextFade(0.0);
   title_fade_label_->SetText(title_label_->GetText());
   title_label_->SetText(title);