events: Update mouse-event handlers to not return EventResult.

ui/views/widget/desktop_aura/desktop_activation_client.cc

Index: ui/views/widget/desktop_aura/desktop_activation_client.cc
diff --git a/ui/views/widget/desktop_aura/desktop_activation_client.cc b/ui/views/widget/desktop_aura/desktop_activation_client.cc
index 181f1dd35912b5a82ada9811401c2a41ab547cde..14bf80e6e128cab8ded9c753c6de558805c52159 100644
--- a/ui/views/widget/desktop_aura/desktop_activation_client.cc
+++ b/ui/views/widget/desktop_aura/desktop_activation_client.cc
@@ -161,10 +161,9 @@ bool DesktopActivationClient::CanActivateWindow(aura::Window* window) const {
 void DesktopActivationClient::OnKeyEvent(ui::KeyEvent* event) {
 }
 
-ui::EventResult DesktopActivationClient::OnMouseEvent(ui::MouseEvent* event) {
+void DesktopActivationClient::OnMouseEvent(ui::MouseEvent* event) {
   if (event->type() == ui::ET_MOUSE_PRESSED)
     FocusWindowWithEvent(event);
-  return ui::ER_UNHANDLED;
 }
 
 void DesktopActivationClient::OnScrollEvent(ui::ScrollEvent* event) {