Add ink drop ripple to overview mode button

ash/common/wm/overview/window_selector_controller.cc

 // Copyright 2013 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 "ash/common/wm/overview/window_selector_controller.h"
 
 #include <vector>
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/system/tray/system_tray_delegate.h"
@@ skipping 24 matching lines @@
   SessionStateDelegate* session_state_delegate =
       WmShell::Get()->GetSessionStateDelegate();
   return session_state_delegate->IsActiveUserSessionStarted() &&
          !session_state_delegate->IsScreenLocked() &&
          !WmShell::Get()->IsSystemModalWindowOpen() &&
          !WmShell::Get()->IsPinned() &&
          WmShell::Get()->system_tray_delegate()->GetUserLoginStatus() !=
              LoginStatus::KIOSK_APP;
 }
 
-void WindowSelectorController::ToggleOverview() {
+bool WindowSelectorController::ToggleOverview() {
   if (IsSelecting()) {
     OnSelectionEnded();
   } else {
     // Don't start overview if window selection is not allowed.
     if (!CanSelect())
-      return;
+      return false;
 
     std::vector<WmWindow*> windows =
         WmShell::Get()->mru_window_tracker()->BuildMruWindowList();
     auto end =
         std::remove_if(windows.begin(), windows.end(),
                        std::not1(std::ptr_fun(&WindowSelector::IsSelectable)));
     windows.resize(end - windows.begin());
 
     // Don't enter overview mode with no windows.
     if (windows.empty())
-      return;
+      return false;
 
     WmShell::Get()->OnOverviewModeStarting();
     window_selector_.reset(new WindowSelector(this));
     window_selector_->Init(windows);
     OnSelectionStarted();
   }
+  return true;
 }
 
 bool WindowSelectorController::IsSelecting() const {
   return window_selector_.get() != NULL;
 }
 
 bool WindowSelectorController::IsRestoringMinimizedWindows() const {
   return window_selector_.get() != NULL &&
          window_selector_->restoring_minimized_windows();
 }
@@ skipping 33 matching lines @@
 }
 
 void WindowSelectorController::OnSelectionStarted() {
   if (!last_selection_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("Ash.WindowSelector.TimeBetweenUse",
                              base::Time::Now() - last_selection_time_);
   }
 }
 
 }  // namespace ash