Not submitted - Fixing invalid visibility states with layers which showed up in unittests ...

ash/wm/overview/window_overview.cc

Index: ash/wm/overview/window_overview.cc
diff --git a/ash/wm/overview/window_overview.cc b/ash/wm/overview/window_overview.cc
index 34d4dc4f194457d0ae635f739780f1d204db40d3..399117ee6986648cb9ab83a67021133648085e7b 100644
--- a/ash/wm/overview/window_overview.cc
+++ b/ash/wm/overview/window_overview.cc
@@ -49,6 +49,10 @@ const int kOverviewSelectorTransitionMilliseconds = 100;
 // The color and opacity of the overview selector.
 const SkColor kWindowOverviewSelectionColor = SK_ColorBLACK;
 const float kWindowOverviewSelectionOpacity = 0.5f;
+// When a window layer gets hidden, and the window remains "logically visible",
+// it is illegal to fade the layer to 0. We therefore use a fraction which is
+// resolving to an alpha of 0 but tells a comparison otherwise.
+const float kWindowLayerNotShown = 0.001f;

[sky, 2014/03/12 19:31:40]

Ugh. Why can't you actually hide here and evervy where?

 
 // The padding or amount of the window selector widget visible around the edges
 // of the currently selected window.
@@ -217,7 +221,7 @@ void WindowOverview::SetSelection(size_t index) {
       old_selection->SetBoundsInScreen(
           GetSelectionBounds(selection_index_) + fade_out_direction,
           dst_display);
-      old_selection->layer()->SetOpacity(0);
+      old_selection->layer()->SetOpacity(kWindowLayerNotShown);
       InitializeSelectionWidget();
       selection_widget_->GetNativeWindow()->SetBoundsInScreen(
           target_bounds - fade_out_direction, dst_display);
@@ -353,7 +357,7 @@ void WindowOverview::HideAndTrackNonOverviewWindows() {
     // Hiding the window can result in it being destroyed.
     if (!hidden_windows_.Contains(*iter))
       continue;
-    (*iter)->layer()->SetOpacity(0);
+    (*iter)->layer()->SetOpacity(kWindowLayerNotShown);
   }
 }
 
@@ -447,7 +451,8 @@ void WindowOverview::InitializeSelectionWidget() {
   selection_widget_->Show();
   selection_widget_->GetNativeWindow()->parent()->StackChildAtBottom(
       selection_widget_->GetNativeWindow());
-  selection_widget_->GetNativeWindow()->layer()->SetOpacity(0);
+  selection_widget_->GetNativeWindow()->layer()->SetOpacity(
+      kWindowLayerNotShown);
 }
 
 gfx::Rect WindowOverview::GetSelectionBounds(size_t index) {