Consolidate two IsArcWindow functions to reduce code duplication

components/arc/BUILD.gn

Index: components/arc/BUILD.gn
diff --git a/components/arc/BUILD.gn b/components/arc/BUILD.gn
index a78e3e625d6ddbc22c237fbd1c46da520f48522e..2599e4a105f05a05b560421c9a5c30212f0a4ae2 100644
--- a/components/arc/BUILD.gn
+++ b/components/arc/BUILD.gn
@@ -116,10 +116,12 @@ static_library("arc_base") {
   ]
 
   deps = [
+    "//ash/shared:app_types",
     "//base",
     "//chromeos",
     "//components/user_manager",
     "//mojo/edk/system",
+    "//ui/aura",

[sadrul, 2017/05/16 18:21:51]

I don't really know what the difference is between arc_base and arc targets. But
do you want to grow a dependency on ash and aura from something called
"arc_base"? Would it make sense to move this into "arc" instead?

[Yusuke Sato, 2017/05/16 21:57:58]

Thanks. Chatted with lhchavez@ and moved them to "arc".

   ]
 
   public_deps = [
@@ -225,6 +227,7 @@ source_set("unit_tests") {
 
   deps = [
     ":arc_test_support",
+    "//ash/shared:app_types",
     "//base",
     "//base/test:test_support",
     "//chromeos",