Add an app_shell_unittests target

extensions/BUILD.gn

Index: extensions/BUILD.gn
diff --git a/extensions/BUILD.gn b/extensions/BUILD.gn
index 0aef2daf6c53756be1c21e691d0e239ab8146bf6..a8ddec33f3c05d57b729b034bf8cef53829dc4fd 100644
--- a/extensions/BUILD.gn
+++ b/extensions/BUILD.gn
@@ -61,9 +61,16 @@ source_set("test_support") {
     "common/value_builder.h",
     "renderer/test_extensions_renderer_client.cc",
     "renderer/test_extensions_renderer_client.h",
-  ]
+    "test/test_extensions_client.cc",
+    "test/test_extensions_client.h",
+    "test/test_permission_message_provider.cc",
+    "test/test_permission_message_provider.h",
+    "test/test_permissions_provider.cc",
+    "test/test_permissions_provider.h",
+   ]
 
   deps = [
+    ":extensions_resources",
     "//base",
     "//extensions/browser",
     "//extensions/common",
@@ -155,13 +162,7 @@ test("unittests") {
     "renderer/script_context_set_unittest.cc",
     "renderer/utils_unittest.cc",
     "test/extensions_unittests_main.cc",
-    "test/test_extensions_client.cc",
-    "test/test_extensions_client.h",
-    "test/test_permission_message_provider.cc",
-    "test/test_permission_message_provider.h",
-    "test/test_permissions_provider.cc",
-    "test/test_permissions_provider.h",
-  ]
+ ]
 
   deps = [
     ":extensions_resources",