Animate the App List overlay when dialogs are opened

ui/app_list/views/app_list_view.cc

Index: ui/app_list/views/app_list_view.cc
diff --git a/ui/app_list/views/app_list_view.cc b/ui/app_list/views/app_list_view.cc
index 55a3b6529bb42fa62834501cd8d73f266101a5a2..b4dcb5884117d9fad6dc6de648ee7d94f7797c74 100644
--- a/ui/app_list/views/app_list_view.cc
+++ b/ui/app_list/views/app_list_view.cc
@@ -221,7 +221,25 @@ void AppListView::UpdateBounds() {
 
 void AppListView::SetAppListOverlayVisible(bool visible) {
   DCHECK(overlay_view_);
-  overlay_view_->SetVisible(visible);
+
+  // Display the overlay immediately so we can begin the animation.
+  overlay_view_->SetVisible(true);
+
+  ui::ScopedLayerAnimationSettings settings(
+      overlay_view_->layer()->GetAnimator());
+  settings.SetTweenType(gfx::Tween::FAST_OUT_SLOW_IN);
+
+  const float kOverlayFadeInMilliseconds = 125;
+  settings.SetTransitionDuration(
+      base::TimeDelta::FromMilliseconds(kOverlayFadeInMilliseconds));
+
+  if (visible == true) {

[calamity, 2014/07/31 07:58:11]

This can just be

if (visible) {

But if you get rid of SetVisible(false) below, you can just use the ternary
operator for the SetOpacity argument.

[sashab, 2014/08/04 01:19:32]

Hmm... I originally thought this might be more confusing. But it looks OK. Done.

+    const float kOverlayOpacity = 0.75f;
+    overlay_view_->layer()->SetOpacity(kOverlayOpacity);
+  } else {
+    overlay_view_->layer()->SetOpacity(0.0f);
+    overlay_view_->SetVisible(false);

[calamity, 2014/07/31 07:58:11]

How does this work? Won't the SetVisible(false) immediately hide the whole view,
messing up the animation?

I think you'll need to observe the animation here.

[sashab, 2014/08/04 01:19:33]

Yup, it works - no matter how long I set the delay, the animation fully
completes before hiding the layer.
The ScopedLayerAnimationSettings must take visibility into account. I can't find
the code for this though...

Also, if you close the dialog while the animation is running, it disappears
instantly.

+  }
 }
 
 bool AppListView::ShouldCenterWindow() const {
@@ -366,12 +384,11 @@ void AppListView::InitAsBubbleInternal(gfx::NativeView parent,
   // To make the overlay view, construct a view with a white background, rather
   // than a white rectangle in it. This is because we need overlay_view_ to be
   // drawn to its own layer (so it appears correctly in the foreground).
-  const float kOverlayOpacity = 0.75f;
   overlay_view_ = new views::View();
   overlay_view_->SetPaintToLayer(true);
-  overlay_view_->layer()->SetOpacity(kOverlayOpacity);
   overlay_view_->SetBoundsRect(GetContentsBounds());
   overlay_view_->SetVisible(false);
+  overlay_view_->layer()->SetOpacity(0.0f);
   // On platforms that don't support a shadow, the rounded border of the app
   // list is constructed _inside_ the view, so a rectangular background goes
   // over the border in the rounded corners. To fix this, give the background a