Add ink drop ripple to overview mode button

ash/common/wm/overview/window_selector_controller.h

Index: ash/common/wm/overview/window_selector_controller.h
diff --git a/ash/common/wm/overview/window_selector_controller.h b/ash/common/wm/overview/window_selector_controller.h
index a8318609fb6015d627d7396f6d09a470621c220b..c0962033dbdb3bee19aa034cd755c828b1ca2e91 100644
--- a/ash/common/wm/overview/window_selector_controller.h
+++ b/ash/common/wm/overview/window_selector_controller.h
@@ -32,8 +32,10 @@ class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
 
   // Enters overview mode. This is essentially the window cycling mode however
   // not released on releasing the alt key and allows selecting with the mouse
-  // or touch rather than keypresses.
-  void ToggleOverview();
+  // or touch rather than keypresses. Returns true if the toggle was successful.

[tdanderson, 2016/11/12 02:18:58]

I think this documentation (which seems a bit out of date) can be trimmed down
to something like:

"Attempts to toggle overview mode and returns true if successful (the toggle
would be unsuccessful if there are no windows to show)."

[mohsen, 2016/11/13 05:10:04]

Right. Done.

+  // If there is no window to show in overview mode, toggle would be
+  // unsuccessful.
+  bool ToggleOverview();
 
   // Returns true if window selection mode is active.
   bool IsSelecting() const;