Add ink drop ripple to overview mode button

ash/common/system/overview/overview_button_tray.cc

Index: ash/common/system/overview/overview_button_tray.cc
diff --git a/ash/common/system/overview/overview_button_tray.cc b/ash/common/system/overview/overview_button_tray.cc
index f88134f04213d3c94ee58a0624651ae6f70a7d93..1d510e389d0eb962735e959ab826fefa90060910 100644
--- a/ash/common/system/overview/overview_button_tray.cc
+++ b/ash/common/system/overview/overview_button_tray.cc
@@ -39,14 +39,15 @@ namespace ash {
 
 OverviewButtonTray::OverviewButtonTray(WmShelf* wm_shelf)
     : TrayBackgroundView(wm_shelf), icon_(nullptr) {
-  SetContentsBackground();
-
   icon_ = new views::ImageView();
   if (MaterialDesignController::IsShelfMaterial()) {
+    SetInkDropMode(InkDropMode::ON);
+    SetContentsBackground(false);
     gfx::ImageSkia image_md =
         CreateVectorIcon(gfx::VectorIconId::SHELF_OVERVIEW, kShelfIconColor);
     icon_->SetImage(image_md);
   } else {
+    SetContentsBackground(true);
     gfx::ImageSkia* image_non_md =
         ui::ResourceBundle::GetSharedInstance().GetImageSkiaNamed(
             IDR_AURA_UBER_TRAY_OVERVIEW_MODE);
@@ -71,10 +72,10 @@ void OverviewButtonTray::UpdateAfterLoginStatusChange(LoginStatus status) {
 bool OverviewButtonTray::PerformAction(const ui::Event& event) {
   WindowSelectorController* controller =
       WmShell::Get()->window_selector_controller();
+  bool was_selecting = controller->IsSelecting();
   controller->ToggleOverview();

[bruthig, 2016/11/11 17:30:40]

nit: Consider changing ToggleOverview() to return a bool to let the caller know
if a Toggle happened.

[mohsen, 2016/11/11 22:37:24]

Done.

-  SetDrawBackgroundAsActive(controller->IsSelecting());
   WmShell::Get()->RecordUserMetricsAction(UMA_TRAY_OVERVIEW);
-  return true;
+  return was_selecting != controller->IsSelecting();

[bruthig, 2016/11/11 17:30:40]

nit: it would be useful to have a comment here as to when this can be false.

[mohsen, 2016/11/11 22:37:24]

Done.

 }
 
 void OverviewButtonTray::SessionStateChanged(
@@ -90,8 +91,12 @@ void OverviewButtonTray::OnMaximizeModeEnded() {
   UpdateIconVisibility();
 }
 
+void OverviewButtonTray::OnOverviewModeStarting() {
+  SetIsActive(true);
+}
+
 void OverviewButtonTray::OnOverviewModeEnded() {
-  SetDrawBackgroundAsActive(false);
+  SetIsActive(false);
 }
 
 void OverviewButtonTray::ClickedOutsideBubble() {}