Pressing spacebar on toolbar buttons triggers the ripple effect.

ui/views/animation/button_ink_drop_delegate.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ui/views/animation/button_ink_drop_delegate.h"
 
 #include "ui/events/event.h"
 #include "ui/events/scoped_target_handler.h"
 #include "ui/views/animation/ink_drop.h"
 #include "ui/views/animation/ink_drop_factory.h"
@@ skipping 17 matching lines @@
 }
 
 void ButtonInkDropDelegate::SnapToActivated() {
   ink_drop_->SnapToActivated();
 }
 
 void ButtonInkDropDelegate::SetHovered(bool is_hovered) {
   ink_drop_->SetHovered(is_hovered);
 }
 
+InkDropState ButtonInkDropDelegate::GetTargetInkDropState() const {
+  return ink_drop_->GetTargetInkDropState();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // ui::EventHandler:
 
 void ButtonInkDropDelegate::OnMouseEvent(ui::MouseEvent* event) {
   switch (event->type()) {
     case ui::ET_MOUSE_ENTERED:
       SetHovered(true);
       break;
     case ui::ET_MOUSE_EXITED:
       SetHovered(false);
@@ skipping 39 matching lines @@
        current_ink_drop_state == InkDropState::DEACTIVATED)) {
     // These InkDropStates automatically transition to the HIDDEN state so we
     // don't make an explicit call. Explicitly animating to HIDDEN in this case
     // would prematurely pre-empt these animations.
     return;
   }
   ink_drop_->AnimateToState(ink_drop_state);
 }
 
 }  // namespace views