Animate the OverviewButtonTray

ash/system/tray/tray_background_view.cc

Index: ash/system/tray/tray_background_view.cc
diff --git a/ash/system/tray/tray_background_view.cc b/ash/system/tray/tray_background_view.cc
index fc24c14932af7c4673e9a46c1d195ce8701d965a..2ece371b25bf16b7cba206f8373882d33ba6fc2c 100644
--- a/ash/system/tray/tray_background_view.cc
+++ b/ash/system/tray/tray_background_view.cc
@@ -22,12 +22,17 @@
 #include "ui/aura/window.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/resource/resource_bundle.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/layer_animation_element.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/gfx/animation/tween.h"
 #include "ui/gfx/canvas.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/gfx/image/image_skia_operations.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/screen.h"
 #include "ui/gfx/skia_util.h"
+#include "ui/gfx/transform.h"
 #include "ui/views/background.h"
 #include "ui/views/layout/box_layout.h"
 
@@ -37,7 +42,15 @@ const int kTrayBackgroundAlpha = 100;
 const int kTrayBackgroundHoverAlpha = 150;
 const SkColor kTrayBackgroundPressedColor = SkColorSetRGB(66, 129, 244);
 
-const int kAnimationDurationForPopupMS = 200;
+const int kAnimationDurationForPopupMs = 200;
+
+// Duration of opacity animation for visibility changes.
+const int kAnimationDurationForVisibilityMs = 250;
+
+// When becoming visible delay the animation so that StatusAreaWidgetDelegate
+// can animate sibling views out of the position to be occuped by the
+// TrayBackgroundView.
+const int kShowAnimationDelayMs = 100;
 
 }  // namespace
 
@@ -307,6 +320,9 @@ TrayBackgroundView::TrayBackgroundView(StatusAreaWidget* status_area_widget)
   tray_container_ = new TrayContainer(shelf_alignment_);
   SetContents(tray_container_);
   tray_event_filter_.reset(new TrayEventFilter);
+
+  SetPaintToLayer(true);
+  SetFillsBoundsOpaquely(false);
 }
 
 TrayBackgroundView::~TrayBackgroundView() {
@@ -319,6 +335,53 @@ void TrayBackgroundView::Initialize() {
   SetTrayBorder();
 }
 
+void TrayBackgroundView::SetVisible(bool visible) {
+  if (visible == this->visible())
+    return;
+
+  if (visible) {
+    // The alignment of the shelf can change while the TrayBackgroundView is
+    // hidden. Reset the offscreen transform so that the animation to becoming
+    // visible reflects the current layout.
+    HideTransformation();
+    // SetVisible(false) is defered until the animation for hiding is done.
+    // Otherwise the view is immediately hidden and the animation does not
+    // render.
+    views::View::SetVisible(visible);
+  }
+
+  layer()->GetAnimator()->StopAnimating();
+  ui::ScopedLayerAnimationSettings animation(layer()->GetAnimator());
+  animation.SetTransitionDuration(base::TimeDelta::FromMilliseconds(
+      kAnimationDurationForVisibilityMs));
+  animation.SetPreemptionStrategy(
+      ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+
+  if (visible) {
+    animation.SetTweenType(gfx::Tween::EASE_OUT);
+    // Show is delayed so as to allow time for other children of
+    // StatusAreaWidget to begin animating to their new positions.
+    layer()->GetAnimator()->SchedulePauseForProperties(
+        base::TimeDelta::FromMilliseconds(kShowAnimationDelayMs),
+        ui::LayerAnimationElement::OPACITY |
+        ui::LayerAnimationElement::TRANSFORM);
+    // layer()->SetVisible(true) is handled by views::View::SetVisible(true) so
+    // we do not need to apply that change while becoming visible.
+    layer()->SetOpacity(1.0f);
+    gfx::Transform transform;
+    transform.Translate(0.0f, 0.0f);
+    layer()->SetTransform(transform);
+  } else {
+    // Listen only to the hide animation. As we cannot turn off visibility
+    // until the animation is over.
+    animation.AddObserver(this);
+    animation.SetTweenType(gfx::Tween::EASE_IN);
+    layer()->SetOpacity(0.0f);
+    layer()->SetVisible(false);
+    HideTransformation();
+  }
+}
+
 const char* TrayBackgroundView::GetClassName() const {
   return kViewClassName;
 }
@@ -420,6 +483,20 @@ void TrayBackgroundView::SetTrayBorder() {
       top_edge, left_edge, bottom_edge, right_edge));
 }
 
+void TrayBackgroundView::OnImplicitAnimationsCompleted() {
+  views::View::SetVisible(false);
+}
+
+void TrayBackgroundView::HideTransformation() {
+  gfx::Transform transform;
+  if (shelf_alignment_ == SHELF_ALIGNMENT_BOTTOM ||
+      shelf_alignment_ == SHELF_ALIGNMENT_TOP)
+    transform.Translate(width(), 0.0f);
+  else
+    transform.Translate(0.0f, height());
+  layer()->SetTransform(transform);
+}
+
 void TrayBackgroundView::InitializeBubbleAnimations(
     views::Widget* bubble_widget) {
   wm::SetWindowVisibilityAnimationType(
@@ -430,7 +507,7 @@ void TrayBackgroundView::InitializeBubbleAnimations(
       wm::ANIMATE_HIDE);
   wm::SetWindowVisibilityAnimationDuration(
       bubble_widget->GetNativeWindow(),
-      base::TimeDelta::FromMilliseconds(kAnimationDurationForPopupMS));
+      base::TimeDelta::FromMilliseconds(kAnimationDurationForPopupMs));
 }
 
 aura::Window* TrayBackgroundView::GetBubbleWindowContainer() const {