Remove RuntimeAPIDelegate::GetPreviousVersion.

extensions/browser/test_runtime_api_delegate.cc

Index: extensions/browser/test_runtime_api_delegate.cc
diff --git a/extensions/browser/test_runtime_api_delegate.cc b/extensions/browser/test_runtime_api_delegate.cc
index d9624b5839d79cb94fb6296177b013b58527694b..1416d49b5409b36484be24e1ccc6185f9a010cf8 100644
--- a/extensions/browser/test_runtime_api_delegate.cc
+++ b/extensions/browser/test_runtime_api_delegate.cc
@@ -22,11 +22,6 @@ void TestRuntimeAPIDelegate::AddUpdateObserver(UpdateObserver* observer) {
 void TestRuntimeAPIDelegate::RemoveUpdateObserver(UpdateObserver* observer) {
 }
 
-base::Version TestRuntimeAPIDelegate::GetPreviousExtensionVersion(
-    const Extension* extension) {
-  return base::Version();
-}
-
 void TestRuntimeAPIDelegate::ReloadExtension(const std::string& extension_id) {
 }