mash: Have chrome set itself as the app list presenter.

ui/app_list/presenter/app_list_presenter.mojom

Index: ui/app_list/presenter/app_list_presenter.mojom
diff --git a/ui/app_list/presenter/app_list_presenter.mojom b/ui/app_list/presenter/app_list_presenter.mojom
index 3ffa45af8f7f9b6eae8ed33a0fcfae5ee5f55ca5..8522ca5805f0992728b2f2cf1163fca4061f30b1 100644
--- a/ui/app_list/presenter/app_list_presenter.mojom
+++ b/ui/app_list/presenter/app_list_presenter.mojom
@@ -6,6 +6,17 @@ module app_list.mojom;
 
 import "services/ui/public/interfaces/window_manager_constants.mojom";
 
+// TODO(msw): Rename this file to app_list.mojom; move to ash?
+// TODO(msw): Ash should implement the app list and presenter; chrome should
+//            just push data about its apps into the app list interface.
+
+// Implemented by ash. Used by chrome to set the presenter interface.
+interface AppList {

[mfomitchev, 2016/12/12 22:59:50]

nit: It would be nice to have a name which would convey the purpose of this
interface a little better. AppListProxy? AppListBinder? AppListBinding?
AppListController (although that could be confusing, since we already have one)?
Would be nice to have consistent naming with the other cases we have a similar
design though (volume/wallpaper/etc), so perhaps something to consider for a
future CL.

[msw, 2016/12/12 23:47:54]

This could be 'AppListPresenterHost', but that just reinforces the existing
complexity and doesn't convey anything terribly useful to casual readers. It
would be more appropriate to call this interface "AppListClient" and rename
"AppListPresenter" to "AppList".

Regardless, ash should ultimately own the app list interface and Chrome should
just inject some app info (similar to what we want for the shelf, see TODO
above), so I'd rather not spend too much effort on naming here.

+  // Set the app list presenter interface, to let ash trigger Chrome's app list.
+  SetAppListPresenter(AppListPresenter presenter);
+};
+
+// Implemented by chrome. Used by ash to actually show and dismiss the app list.
 interface AppListPresenter {
   // Show the app list on the specified display.
   Show(int64 display_id);