mash: Use ash shell window container ids instead of ash::mojom::Container

ash/shared/BUILD.gn

Index: ash/shared/BUILD.gn
diff --git a/ash/shared/BUILD.gn b/ash/shared/BUILD.gn
index 3bfae4f1a6ccb54d3df97921e9089212ec3921c6..f0cfab706dd1897ef92637528345063a9ee82587 100644
--- a/ash/shared/BUILD.gn
+++ b/ash/shared/BUILD.gn
@@ -2,8 +2,14 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-source_set("app_types") {
+source_set("shared") {

[sky, 2016/10/18 02:45:53]

As this is a source_set there isn't any point in the ASH_SHARED_EXPORT. Also, I
think we should keep logically unrelated source files in separate source_sets. I
say this as it's very unlikely that all apps want all the files in this
directory.

[James Cook, 2016/10/18 04:45:45]

Whoops, I uploaded the ash_shared_export.h file by mistake from an earlier
patch. I never actually used the macro it defines.

I split the shell_window_ids files into their own source set. I put
//ash/shared:shell_window_ids into public_deps for targets that include
shell_window_ids.h inside their headers, and in regular deps for those than only
use it in .cc files.

   sources = [
     "app_types.h",
+    "shell_window_ids.cc",
+    "shell_window_ids.h",
+  ]
+
+  deps = [
+    "//base",
   ]
 }