Make chrome_shell_apk build

extensions/BUILD.gn

Index: extensions/BUILD.gn
diff --git a/extensions/BUILD.gn b/extensions/BUILD.gn
index a6b9d09b31a5ab6c97f431ce9b6ad01ec327e99a..f0026dc176992c9752332c885814578bd2bd9aef 100644
--- a/extensions/BUILD.gn
+++ b/extensions/BUILD.gn
@@ -47,13 +47,16 @@ grit("extensions_renderer_resources") {
     "extensions_renderer_resources.pak",
   ]
   grit_flags = [ "-E", "mojom_root=" + rebase_path(root_gen_dir) ]
-  if (enable_extensions) {
-    deps = [
-      "//device/serial:serial_mojo",
-    ]
-  }
+
+  # TODO(GYP,cjhopman): GYP has this dependency guarded by enable_extensions==1,
+  # but I don't know how that possibly works.
+  deps = [
+    "//device/serial:serial_mojo",
+  ]
 }
 
+if (enable_extensions) {
+
 source_set("test_support") {
   testonly = true
   sources = [
@@ -264,3 +267,5 @@ test("extensions_unittests") {
   }
 }
 }
+
+}