Pressing spacebar on toolbar buttons triggers the ripple effect.

ui/views/controls/button/custom_button.cc

Index: ui/views/controls/button/custom_button.cc
diff --git a/ui/views/controls/button/custom_button.cc b/ui/views/controls/button/custom_button.cc
index 770f92ff16dcf521f4af1e43de27e957f57d1202..527a6d82093dae2edb9635960c47b3ff1a206ccf 100644
--- a/ui/views/controls/button/custom_button.cc
+++ b/ui/views/controls/button/custom_button.cc
@@ -268,6 +268,10 @@ bool CustomButton::OnKeyPressed(const ui::KeyEvent& event) {
   // KeyRelease and Enter clicks the button on KeyPressed.
   if (event.key_code() == ui::VKEY_SPACE) {
     SetState(STATE_PRESSED);
+    if (ink_drop_delegate_ &&
+        ink_drop_delegate_->GetTargetInkDropState() !=
+            views::InkDropState::ACTION_PENDING)
+      ink_drop_delegate_->OnAction(views::InkDropState::ACTION_PENDING);
   } else if (event.key_code() == ui::VKEY_RETURN) {
     SetState(STATE_NORMAL);
     NotifyClick(event);