Re-reland: chromeos: Fix shelf appearing at login screen under mash

ash/common/wm_shell.h

Index: ash/common/wm_shell.h
diff --git a/ash/common/wm_shell.h b/ash/common/wm_shell.h
index a5589c97dc72bbb9f31cfa895da91c242b77ccf4..ae07822cef817eaf1e236534248dbc1e84e4e14e 100644
--- a/ash/common/wm_shell.h
+++ b/ash/common/wm_shell.h
@@ -13,6 +13,7 @@
 #include "ash/ash_export.h"
 #include "ash/common/metrics/gesture_action_type.h"
 #include "ash/common/metrics/user_metrics_action.h"
+#include "ash/common/session/session_state_observer.h"
 #include "ash/common/wm/lock_state_observer.h"
 #include "base/observer_list.h"
 #include "components/ui_devtools/devtools_server.h"
@@ -101,7 +102,7 @@ class WindowState;
 }
 
 // Similar to ash::Shell. Eventually the two will be merged.
-class ASH_EXPORT WmShell {
+class ASH_EXPORT WmShell : public SessionStateObserver {
  public:
   // This is necessary for a handful of places that is difficult to plumb
   // through context.
@@ -353,12 +354,10 @@ class ASH_EXPORT WmShell {
 
   virtual std::unique_ptr<KeyEventWatcher> CreateKeyEventWatcher() = 0;
 
-  // Initializes the appropriate shelves. Does nothing for any existing shelves.
+  // Creates the ShelfView for each display and populates it with items.
+  // TODO(jamescook): Rename this. http://crbug.com/679925
   void CreateShelf();
 
-  // Show shelf view if it was created hidden (before session has started).
-  void ShowShelf();
-
   void CreateShelfDelegate();
 
   // Called after maximize mode has started, windows might still animate though.
@@ -447,7 +446,7 @@ class ASH_EXPORT WmShell {
 
  protected:
   explicit WmShell(std::unique_ptr<ShellDelegate> shell_delegate);
-  virtual ~WmShell();
+  ~WmShell() override;
 
   base::ObserverList<ShellObserver>* shell_observers() {
     return &shell_observers_;
@@ -475,6 +474,9 @@ class ASH_EXPORT WmShell {
   void SetAcceleratorController(
       std::unique_ptr<AcceleratorController> accelerator_controller);
 
+  // SessionStateObserver:
+  void SessionStateChanged(session_manager::SessionState state) override;
+
  private:
   friend class AcceleratorControllerTest;
   friend class ScopedRootWindowForNewWindows;