Animate the App List overlay when dialogs are opened

Currently, the App List overlay opens and closes without animating. This
looks strange the dialog itself animates as it opens. Add an animation
delay so the overlay animates slowly open to match the sub-dialogs.

BUG=395494

Review URL: https://codereview.chromium.org/429823002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@287492 0039d316-1c4b-4281-b951-d872f2087c98

ui/app_list/views/app_list_view.cc

@@ -118,7 +118,7 @@ class HideViewAnimationObserver : public ui::ImplicitAnimationObserver {
   }
 
   void SetTarget(views::View* target) {
-    if (!target_)
+    if (target_)
       StopObservingImplicitAnimations();
     target_ = target;
   }
@@ -133,7 +133,8 @@ class HideViewAnimationObserver : public ui::ImplicitAnimationObserver {
       target_ = NULL;
 
       // Should update the background by invoking SchedulePaint().
-      frame_->SchedulePaint();
+      if (frame_)
+        frame_->SchedulePaint();
     }
   }
 
@@ -221,7 +222,29 @@ 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::LINEAR);
+
+  // If we're dismissing the overlay, hide the view at the end of the animation.
+  if (!visible) {
+    // Since only one animation is visible at a time, it's safe to re-use
+    // animation_observer_ here.
+    animation_observer_->set_frame(NULL);
+    animation_observer_->SetTarget(overlay_view_);
+    settings.AddObserver(animation_observer_.get());
+  }
+
+  const float kOverlayFadeInMilliseconds = 125;
+  settings.SetTransitionDuration(
+      base::TimeDelta::FromMilliseconds(kOverlayFadeInMilliseconds));
+
+  const float kOverlayOpacity = 0.75f;
+  overlay_view_->layer()->SetOpacity(visible ? kOverlayOpacity : 0.0f);
 }
 
 bool AppListView::ShouldCenterWindow() const {
@@ -366,12 +389,11 @@ 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