Cleanup shelf initialization and observation.

ash/shelf/shelf.cc

Index: ash/shelf/shelf.cc
diff --git a/ash/shelf/shelf.cc b/ash/shelf/shelf.cc
index 538510e540fc370d75f48badf0214642774cc19b..8d96506970a50dff103120bce9c370741bd1a1d3 100644
--- a/ash/shelf/shelf.cc
+++ b/ash/shelf/shelf.cc
@@ -42,15 +42,15 @@ const char Shelf::kNativeViewName[] = "ShelfView";
 Shelf::Shelf(ShelfModel* shelf_model,
              ShelfDelegate* shelf_delegate,
              ShelfWidget* shelf_widget)
-    : shelf_view_(NULL),
-      alignment_(shelf_widget->GetAlignment()),
+    : shelf_view_(nullptr),
+      alignment_(SHELF_ALIGNMENT_BOTTOM),
+      auto_hide_behavior_(SHELF_AUTO_HIDE_BEHAVIOR_NEVER),
       delegate_(shelf_delegate),
       shelf_widget_(shelf_widget) {
   shelf_view_ = new ShelfView(shelf_model, delegate_, this);
   shelf_view_->Init();
   shelf_widget_->GetContentsView()->AddChildView(shelf_view_);
   shelf_widget_->GetNativeView()->SetName(kNativeViewName);
-  delegate_->OnShelfCreated(this);
 }
 
 Shelf::~Shelf() {
@@ -65,25 +65,44 @@ Shelf* Shelf::ForPrimaryDisplay() {
 // static
 Shelf* Shelf::ForWindow(const aura::Window* window) {
   ShelfWidget* shelf_widget = RootWindowController::ForWindow(window)->shelf();
-  return shelf_widget ? shelf_widget->shelf() : NULL;
+  return shelf_widget ? shelf_widget->shelf() : nullptr;
 }
 
 void Shelf::SetAlignment(ShelfAlignment alignment) {
+  if (alignment_ == alignment)
+    return;
+
   alignment_ = alignment;
   shelf_view_->OnShelfAlignmentChanged();
+  shelf_widget_->OnShelfAlignmentChanged();
+  delegate_->OnShelfAlignmentChanged(this);
+  Shell::GetInstance()->OnShelfAlignmentChanged(
+      shelf_widget_->GetNativeWindow()->GetRootWindow());
   // ShelfLayoutManager will resize the shelf.
 }
 
+ShelfAlignment Shelf::GetAlignment() const {
+  // Bottom alignment is forced when the screen is locked or a user gets added.
+  bool locked = shelf_widget_->shelf_layout_manager()->IsAlignmentLocked();
+  return locked ? SHELF_ALIGNMENT_BOTTOM : alignment_;

[sky, 2016/04/04 22:44:32]

Seems unusual to force an alignment like this. Couldn't the code explicitly set
the alignment to bottom when necessary? Doing that ensures delegates and what
not are notified when locking if the alignment wasn't bottom.

+}
+
 bool Shelf::IsHorizontalAlignment() const {
   return alignment_ == SHELF_ALIGNMENT_BOTTOM;
 }
 
-void Shelf::SetAutoHideBehavior(ShelfAutoHideBehavior behavior) {
-  shelf_widget_->shelf_layout_manager()->SetAutoHideBehavior(behavior);
+void Shelf::SetAutoHideBehavior(ShelfAutoHideBehavior auto_hide_behavior) {
+  if (auto_hide_behavior_ == auto_hide_behavior)
+    return;
+
+  auto_hide_behavior_ = auto_hide_behavior;
+  delegate_->OnShelfAutoHideBehaviorChanged(this);
+  Shell::GetInstance()->OnShelfAutoHideBehaviorChanged(
+      shelf_widget_->GetNativeWindow()->GetRootWindow());
 }
 
 ShelfAutoHideBehavior Shelf::GetAutoHideBehavior() const {
-  return shelf_widget_->shelf_layout_manager()->auto_hide_behavior();
+  return auto_hide_behavior_;
 }
 
 gfx::Rect Shelf::GetScreenBoundsOfItemIconForWindow(