[AF] Initialize security_level in save_card_bubble_..._unittests.

Was causing failures on MSAN bots.

Change-Id: Icbffe8066bed645404fa792992f84e62ed1e83ca
Reviewed-on: https://chromium-review.googlesource.com/1112064Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Sebastien Seguin-Gagnon <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569769}

chrome/browser/ui/autofill/save_card_bubble_controller_impl_unittest.cc

@@ -64,7 +64,8 @@ class TestSaveCardBubbleControllerImpl : public SaveCardBubbleControllerImpl {
 
  private:
   base::TimeDelta elapsed_;
-  security_state::SecurityLevel security_level_;
+  security_state::SecurityLevel security_level_ =
+      security_state::SecurityLevel::NONE;
 };
 
 class SaveCardBubbleControllerImplTest : public BrowserWithTestWindowTest {