Makes AshTestImpl::Create create the right impl based on config

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index e8a94058a80200bc72c72414c3126c0fae6e193f..3902fec089b166fb3d1ba27cb451bdc43d0e032a 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -240,7 +240,6 @@ static_library("test_support") {
 
     public_deps += [
       "//ash",
-      "//ash/test:ash_with_aura_test_support",
       "//ash/test:test_support_with_content",
       "//ui/aura",
       "//ui/aura:test_support",
@@ -2127,7 +2126,6 @@ test("browser_tests") {
         "../browser/ui/views/frame/browser_non_client_frame_view_ash_browsertest.cc",
       ]
       deps += [
-        "//ash/test:ash_with_aura_test_support",
         "//ash/test:test_support_with_content",
         "//ui/keyboard:test_support",
       ]
@@ -4211,7 +4209,6 @@ test("unit_tests") {
     deps += [
       "//ash/resources",
       "//ash/strings",
-      "//ash/test:ash_with_aura_test_support",
       "//ash/test:test_support_with_content",
     ]