Overview Button Tray Animation accounting for startup

ash/system/status_area_widget_delegate.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/system/status_area_widget_delegate.h"
 
 #include "ash/ash_export.h"
 #include "ash/ash_switches.h"
 #include "ash/focus_cycler.h"
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/system/tray/tray_constants.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/strings/utf_string_conversions.h"
 #include "ui/aura/window_event_dispatcher.h"
 #include "ui/base/resource/resource_bundle.h"
+#include "ui/compositor/layer.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.h"
 #include "ui/views/accessible_pane_view.h"
 #include "ui/views/layout/grid_layout.h"
 #include "ui/views/widget/widget.h"
 
+namespace {
+
+const int kAnimationDurationMs = 250;
+
+class StatusAreaWidgetDelegateAnimationSettings
+    : public ui::ScopedLayerAnimationSettings {
+ public:
+  explicit StatusAreaWidgetDelegateAnimationSettings(ui::Layer* layer)
+      : ui::ScopedLayerAnimationSettings(layer->GetAnimator()) {
+    SetTransitionDuration(
+        base::TimeDelta::FromMilliseconds(kAnimationDurationMs));
+    SetPreemptionStrategy(
+        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+    SetTweenType(gfx::Tween::EASE_IN_OUT);
+  }
+
+  virtual ~StatusAreaWidgetDelegateAnimationSettings() {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(StatusAreaWidgetDelegateAnimationSettings);
+};
+
+}  // namespace
+
 namespace ash {
 
 StatusAreaWidgetDelegate::StatusAreaWidgetDelegate()
     : focus_cycler_for_testing_(NULL),
       alignment_(SHELF_ALIGNMENT_BOTTOM) {
   // Allow the launcher to surrender the focus to another window upon
   // navigation completion by the user.
   set_allow_deactivate_on_esc(true);
+  SetPaintToLayer(true);
+  SetFillsBoundsOpaquely(false);
 }
 
 StatusAreaWidgetDelegate::~StatusAreaWidgetDelegate() {
 }
 
 void StatusAreaWidgetDelegate::SetFocusCyclerForTesting(
     const FocusCycler* focus_cycler) {
   focus_cycler_for_testing_ = focus_cycler;
 }
 
@@ skipping 70 matching lines @@
       views::View* child = child_at(c);
       if (!child->visible())
         continue;
       if (!is_first_visible_child)
         layout->AddPaddingRow(0, kTraySpacing);
       is_first_visible_child = false;
       layout->StartRow(0, 0);
       layout->AddView(child);
     }
   }
+
+  layer()->GetAnimator()->StopAnimating();
+  StatusAreaWidgetDelegateAnimationSettings settings(layer());
+
   Layout();
   UpdateWidgetSize();
 }
 
 void StatusAreaWidgetDelegate::ChildPreferredSizeChanged(View* child) {
   // Need to resize the window when trays or items are added/removed.
+  StatusAreaWidgetDelegateAnimationSettings settings(layer());
   UpdateWidgetSize();
 }
 
 void StatusAreaWidgetDelegate::ChildVisibilityChanged(View* child) {
   UpdateLayout();
 }
 
 void StatusAreaWidgetDelegate::UpdateWidgetSize() {
   if (GetWidget())
     GetWidget()->SetSize(GetPreferredSize());
 }
 
 }  // namespace ash