Pressing spacebar on toolbar buttons triggers the ripple effect.

ui/views/controls/button/custom_button_unittest.cc

 // Copyright (c) 2012 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/controls/button/custom_button.h"
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "build/build_config.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ skipping 76 matching lines @@
 
 // An InkDropDelegate that keeps track of ink drop visibility.
 class TestInkDropDelegateThatTracksVisibilty : public InkDropDelegate {
  public:
   TestInkDropDelegateThatTracksVisibilty(bool* ink_shown, bool* ink_hidden)
       : ink_shown_(ink_shown), ink_hidden_(ink_hidden) {}
   ~TestInkDropDelegateThatTracksVisibilty() override {}
 
   // InkDropDelegate:
   void OnAction(InkDropState state) override {
-    switch (state) {
+    state_ = state;
+    switch (state_) {
       case InkDropState::ACTION_PENDING:
       case InkDropState::ALTERNATE_ACTION_PENDING:
       case InkDropState::ACTIVATED:
         *ink_shown_ = true;
         break;
       case InkDropState::HIDDEN:
         *ink_hidden_ = true;
         break;
       case InkDropState::ACTION_TRIGGERED:
       case InkDropState::ALTERNATE_ACTION_TRIGGERED:
       case InkDropState::DEACTIVATED:
         break;
     }
   }
 
   void SnapToActivated() override { *ink_shown_ = true; }
 
   void SetHovered(bool is_hovered) override {}
 
+  InkDropState GetTargetInkDropState() const override { return state_; }

[bruthig, 2016/05/14 00:17:24]

Can you update TestInkDropDelegateThatTracksVisibilty to extend from
TestInkDropDelegate instead and make use of it's new
InkDropState::GetTargetInkDropState()?

+
  private:
   bool* ink_shown_;
   bool* ink_hidden_;
+  InkDropState state_;
 
   DISALLOW_COPY_AND_ASSIGN(TestInkDropDelegateThatTracksVisibilty);
 };
 
 // A test Button class that owns a TestInkDropDelegate.
 class TestButtonWithInkDrop : public TestCustomButton {
  public:
   TestButtonWithInkDrop(std::unique_ptr<InkDropDelegate> ink_drop_delegate)
       : TestCustomButton(), ink_drop_delegate_(std::move(ink_drop_delegate)) {
     set_ink_drop_delegate(ink_drop_delegate_.get());
@@ skipping 311 matching lines @@
   TestContextMenuController context_menu_controller;
   button()->set_context_menu_controller(&context_menu_controller);
   button()->set_hide_ink_drop_when_showing_context_menu(true);
 
   ink_drop_delegate->SetHovered(true);
   ink_drop_delegate->OnAction(InkDropState::ACTION_PENDING);
 
   button()->ShowContextMenu(gfx::Point(), ui::MENU_SOURCE_MOUSE);
 
   EXPECT_FALSE(ink_drop_delegate->is_hovered());
-  EXPECT_EQ(InkDropState::HIDDEN, ink_drop_delegate->state());
+  EXPECT_EQ(InkDropState::HIDDEN, ink_drop_delegate->GetTargetInkDropState());
 }
 
 TEST_F(CustomButtonTest, DontHideInkDropWhenShowingContextMenu) {
   TestInkDropDelegate* ink_drop_delegate = new TestInkDropDelegate();
   CreateButtonWithInkDrop(base::WrapUnique(ink_drop_delegate));
   TestContextMenuController context_menu_controller;
   button()->set_context_menu_controller(&context_menu_controller);
   button()->set_hide_ink_drop_when_showing_context_menu(false);
 
   ink_drop_delegate->SetHovered(true);
   ink_drop_delegate->OnAction(InkDropState::ACTION_PENDING);
 
   button()->ShowContextMenu(gfx::Point(), ui::MENU_SOURCE_MOUSE);
 
   EXPECT_TRUE(ink_drop_delegate->is_hovered());
-  EXPECT_EQ(InkDropState::ACTION_PENDING, ink_drop_delegate->state());
+  EXPECT_EQ(InkDropState::ACTION_PENDING,
+            ink_drop_delegate->GetTargetInkDropState());
 }
 
 TEST_F(CustomButtonTest, InkDropAfterTryingToShowContextMenu) {
   TestInkDropDelegate* ink_drop_delegate = new TestInkDropDelegate();
   CreateButtonWithInkDrop(base::WrapUnique(ink_drop_delegate));
   button()->set_context_menu_controller(nullptr);
 
   ink_drop_delegate->SetHovered(true);
   ink_drop_delegate->OnAction(InkDropState::ACTION_PENDING);
 
   button()->ShowContextMenu(gfx::Point(), ui::MENU_SOURCE_MOUSE);
 
   EXPECT_TRUE(ink_drop_delegate->is_hovered());
-  EXPECT_EQ(InkDropState::ACTION_PENDING, ink_drop_delegate->state());
+  EXPECT_EQ(InkDropState::ACTION_PENDING,
+            ink_drop_delegate->GetTargetInkDropState());
 }
 
 }  // namespace views