Added an ActivationReason parameter to ActivationChangeObserver::OnWindowActivated(...).

ash/test/test_activation_delegate.h

Index: ash/test/test_activation_delegate.h
diff --git a/ash/test/test_activation_delegate.h b/ash/test/test_activation_delegate.h
index 702e4f98c0c0bec2c1ffee55d623f312864e75d9..9c3ddbb8654d43ccb1014cbbf28291d4af6c6cd9 100644
--- a/ash/test/test_activation_delegate.h
+++ b/ash/test/test_activation_delegate.h
@@ -44,8 +44,10 @@ class TestActivationDelegate : public aura::client::ActivationDelegate,
 
  private:
   // Overridden from aura::client::ActivationChangeObserver:
-  void OnWindowActivated(aura::Window* gained_active,
-                         aura::Window* lost_active) override;
+  void OnWindowActivated(
+      aura::client::ActivationChangeObserver::ActivationReason reason,
+      aura::Window* gained_active,
+      aura::Window* lost_active) override;
 
   aura::Window* window_;
   bool window_was_active_;