Show the Cast toolbar icon ephemerally when Cast is in use

chrome/browser/ui/toolbar/toolbar_actions_model.cc

Index: chrome/browser/ui/toolbar/toolbar_actions_model.cc
diff --git a/chrome/browser/ui/toolbar/toolbar_actions_model.cc b/chrome/browser/ui/toolbar/toolbar_actions_model.cc
index 7f2317370ad27c596cc182e0eef1334ae1ab6112..6ad8d164e234f9733bc01f565efde81df79d87d9 100644
--- a/chrome/browser/ui/toolbar/toolbar_actions_model.cc
+++ b/chrome/browser/ui/toolbar/toolbar_actions_model.cc
@@ -343,7 +343,7 @@ void ToolbarActionsModel::AddItem(const ToolbarItem& item, bool is_component) {
   // extensions go at their previous position.
   size_t new_index = 0;
   if (is_new_extension) {
-    new_index = is_component ? 0 : visible_icon_count();

[msw, 2016/07/26 19:59:32]

nit: note this tangential behavior change in the CL description.

[Devlin, 2016/07/26 21:59:03]

FYI, this also breaks behavior we had in place for stars.  That's probably no
longer as important given stars isn't bundled with chrome, but it might be worth
discussing.

[takumif, 2016/07/28 20:04:11]

I wasn't aware that there are/were component actions in development other than
MR. Was this behavior implemented specifically for Stars?

[Devlin, 2016/07/29 19:10:22]

Yes, this was just for stars, so I think we're probably okay on that front.  At
the very least though, we should mention this change in the CL description.

[takumif, 2016/08/02 04:58:41]

Done changing the description.

+    new_index = visible_icon_count();
     // For the last-known position, we use the index of the extension that is
     // just before this extension, plus one. (Note that this isn't the same
     // as new_index + 1, because last_known_positions_ can include disabled