Make sure that a given app/extension requests only its own resources.

chrome/browser/extensions/extension_function_test_utils.h

Index: chrome/browser/extensions/extension_function_test_utils.h
diff --git a/chrome/browser/extensions/extension_function_test_utils.h b/chrome/browser/extensions/extension_function_test_utils.h
index 7bcf84d4b043f5ff47255f184dd155a24e987401..b48fc1233dd7efdaa5a5354325ab149d69d0dd64 100644
--- a/chrome/browser/extensions/extension_function_test_utils.h
+++ b/chrome/browser/extensions/extension_function_test_utils.h
@@ -54,6 +54,16 @@ scoped_refptr<extensions::Extension> CreateEmptyExtension();
 scoped_refptr<extensions::Extension> CreateEmptyExtensionWithLocation(
     extensions::Extension::Location location);
 
+// Creates an empty extension with a variable ID, for tests that require
+// multiple extensions side-by-side having distinct IDs. If not empty, then
+// id_input is passed directly to Extension::CreateId() and thus has the same
+// behavior as that method. If id_input is empty, then Extension::Create()
+// receives an empty explicit ID and generates an appropriate ID for a blank
+// extension.
+scoped_refptr<extensions::Extension> CreateEmptyExtension(
+    extensions::Extension::Location location,
+    const std::string& id_input);
+
 enum RunFunctionFlags {
   NONE = 0,
   INCLUDE_INCOGNITO = 1 << 0