Fixing invalid visibility states with layers (opacity==0, visibility==true)

ash/wm/panels/panel_layout_manager.cc

Index: ash/wm/panels/panel_layout_manager.cc
diff --git a/ash/wm/panels/panel_layout_manager.cc b/ash/wm/panels/panel_layout_manager.cc
index 690c23ace74a606191237ec10af75fa89875fcda..14dd477e4057bd0c22e09c9ff5f484d41240faef 100644
--- a/ash/wm/panels/panel_layout_manager.cc
+++ b/ash/wm/panels/panel_layout_manager.cc
@@ -848,16 +848,13 @@ void PanelLayoutManager::UpdateCallouts() {
     SetChildBoundsDirect(callout_widget->GetNativeWindow(), callout_bounds);
     panel_container_->StackChildAbove(callout_widget->GetNativeWindow(),
                                       panel);
-    callout_widget->Show();
 
     ui::Layer* layer = callout_widget->GetNativeWindow()->layer();
     // If the panel is not over the callout position or has just become visible
     // then fade in the callout.
-    if ((distance_until_over_panel > 0 || layer->GetTargetOpacity() < 1) &&
-        panel->layer()->GetTargetTransform().IsIdentity()) {
+    if ((distance_until_over_panel > 0 || layer->GetTargetOpacity() < 1)) {
       if (distance_until_over_panel > 0 &&
           slide_distance >= distance_until_over_panel) {
-        layer->SetOpacity(0);
         // If the panel is not yet over the callout, then delay fading in
         // the callout until after the panel should be over it.
         int delay = kPanelSlideDurationMilliseconds *
@@ -868,16 +865,17 @@ void PanelLayoutManager::UpdateCallouts() {
             base::TimeDelta::FromMilliseconds(delay),
             ui::LayerAnimationElement::OPACITY);
       }
-      {
-        ui::ScopedLayerAnimationSettings callout_settings(layer->GetAnimator());
-        callout_settings.SetPreemptionStrategy(
-            ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
-        callout_settings.SetTransitionDuration(
-            base::TimeDelta::FromMilliseconds(
-                kCalloutFadeDurationMilliseconds));
-        layer->SetOpacity(1);
-      }
+      ui::ScopedLayerAnimationSettings callout_settings(layer->GetAnimator());
+      callout_settings.SetPreemptionStrategy(
+          ui::LayerAnimator::REPLACE_QUEUED_ANIMATIONS);
+      callout_settings.SetTransitionDuration(
+          base::TimeDelta::FromMilliseconds(
+              kCalloutFadeDurationMilliseconds));
+      layer->SetOpacity(1);
     }
+
+    // Show the window after we have started the opacity animation.

[sky, 2014/03/18 20:13:11]

I'll say it again, don't document what the code does, document why, eg:

// Show after changing the opacity, this way we don't have a state
// where the widget is visible but the opacity is 0.

[Mr4D (OOO till 08-26), 2014/03/18 21:32:05]

Done. 

+    callout_widget->Show();
   }
 }