mash: Preliminary support for shelf auto-hide

ash/mus/shelf_delegate_mus.cc

Index: ash/mus/shelf_delegate_mus.cc
diff --git a/ash/mus/shelf_delegate_mus.cc b/ash/mus/shelf_delegate_mus.cc
index 2b11d7cbd04f62e7fef06fe6b0eef135b7ebeb01..47c4adc0de1a151e860091c4dd6776df547025ab 100644
--- a/ash/mus/shelf_delegate_mus.cc
+++ b/ash/mus/shelf_delegate_mus.cc
@@ -193,11 +193,16 @@ ShelfDelegateMus::ShelfDelegateMus(ShelfModel* model)
 
 ShelfDelegateMus::~ShelfDelegateMus() {}
 
+///////////////////////////////////////////////////////////////////////////////
+// ShelfDelegate:
+
 void ShelfDelegateMus::OnShelfCreated(Shelf* shelf) {
   SetShelfPreferredSizes(shelf);
+  shelf->shelf_layout_manager()->AddObserver(this);
 }
 
 void ShelfDelegateMus::OnShelfDestroyed(Shelf* shelf) {
+  shelf->shelf_layout_manager()->RemoveObserver(this);
   NOTIMPLEMENTED();
 }
 
@@ -254,6 +259,26 @@ void ShelfDelegateMus::UnpinAppWithID(const std::string& app_id) {
   NOTIMPLEMENTED();
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// ShelfLayoutManagerObserver:
+
+void ShelfDelegateMus::DidChangeVisibilityState(
+    ShelfLayoutManager* layout_manager,
+    ShelfVisibilityState new_state) {
+  // Push the new preferred size to the window manager. For example, when the
+  // shelf is auto-hidden it becomes a very short "light bar".
+  SetShelfPreferredSizes(layout_manager->shelf_widget()->shelf());
+}
+
+void ShelfDelegateMus::OnAutoHideStateChanged(
+    ShelfLayoutManager* layout_manager,
+    ShelfAutoHideState new_state) {
+  SetShelfPreferredSizes(layout_manager->shelf_widget()->shelf());
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// mash::shelf::mojom::ShelfController:
+
 void ShelfDelegateMus::AddObserver(
     mash::shelf::mojom::ShelfObserverAssociatedPtrInfo observer) {
   mash::shelf::mojom::ShelfObserverAssociatedPtr observer_ptr;
@@ -451,7 +476,7 @@ void ShelfDelegateMus::SetShelfPreferredSizes(Shelf* shelf) {
   ShelfWidget* widget = shelf->shelf_widget();
   ShelfLayoutManager* layout_manager = widget->shelf_layout_manager();
   mus::Window* window = aura::GetMusWindow(widget->GetNativeWindow());
-  gfx::Size size = layout_manager->GetIdealBounds().size();
+  gfx::Size size = layout_manager->GetPreferredSize();
   window->SetSharedProperty<gfx::Size>(
       mus::mojom::WindowManager::kPreferredSize_Property, size);