4 files changed, 12 insertions, 2 deletions
diff --git a/ash/display/window_tree_host_manager.cc b/ash/display/window_tree_host_manager.cc
index af7d17c..aabf1b2 100644
--- a/ash/display/window_tree_host_manager.cc
+++ b/ash/display/window_tree_host_manager.cc
@@ -286,6 +286,8 @@ void WindowTreeHostManager::Start() {
 }
 
 void WindowTreeHostManager::Shutdown() {
+  FOR_EACH_OBSERVER(Observer, observers_, OnWindowTreeHostManagerShutdown());
+
   // Unset the display manager's delegate here because
   // DisplayManager outlives WindowTreeHostManager.
   Shell::GetInstance()->display_manager()->set_delegate(nullptr);
diff --git a/ash/display/window_tree_host_manager.h b/ash/display/window_tree_host_manager.h
index 5d27699..67ae28d 100644
--- a/ash/display/window_tree_host_manager.h
+++ b/ash/display/window_tree_host_manager.h
@@ -72,7 +72,10 @@ class ASH_EXPORT WindowTreeHostManager
 
     // Invoked when the all display configuration changes
     // have been applied.
-    virtual void OnDisplayConfigurationChanged(){};
+    virtual void OnDisplayConfigurationChanged() {}
+
+    // Invoked in WindowTreeHostManager::Shutdown().
+    virtual void OnWindowTreeHostManagerShutdown() {}
 
    protected:
     virtual ~Observer() {}
@@ -225,7 +228,7 @@ class ASH_EXPORT WindowTreeHostManager
   // The mapping from display ID to its window tree host.
   WindowTreeHostMap window_tree_hosts_;
 
-  base::ObserverList<Observer> observers_;
+  base::ObserverList<Observer, true> observers_;
 
   // Store the primary window tree host temporarily while replacing
   // display.
diff --git a/ash/shell.cc b/ash/shell.cc
index 27697f6..b021e7b 100644
--- a/ash/shell.cc
+++ b/ash/shell.cc
@@ -1077,6 +1077,8 @@ void Shell::Init(const ShellInitParams& init_params) {
   // is started.
   display_manager_->CreateMirrorWindowAsyncIfAny();
 
+  FOR_EACH_OBSERVER(ShellObserver, observers_, OnShellInitialized());
+
   user_metrics_recorder_->OnShellInitialized();
 }
 
diff --git a/ash/shell_observer.h b/ash/shell_observer.h
index 3ea105b..da53428 100644
--- a/ash/shell_observer.h
+++ b/ash/shell_observer.h
@@ -63,6 +63,9 @@ class ASH_EXPORT ShellObserver {
   // animating but have been restored.
   virtual void OnMaximizeModeEnded() {}
 
+  // Called at the end of Shell::Init.
+  virtual void OnShellInitialized() {}
+
  protected:
   virtual ~ShellObserver() {}
 };