Add "previewing on hover" support for password field.

components/autofill/core/browser/test_autofill_driver.cc

Index: components/autofill/core/browser/test_autofill_driver.cc
diff --git a/components/autofill/core/browser/test_autofill_driver.cc b/components/autofill/core/browser/test_autofill_driver.cc
index a5901cfca6768a9ad116e111b4621c19dba8bb08..9e82f271a93c1481a26c651783c52dd940202937 100644
--- a/components/autofill/core/browser/test_autofill_driver.cc
+++ b/components/autofill/core/browser/test_autofill_driver.cc
@@ -51,6 +51,10 @@ void TestAutofillDriver::RendererShouldAcceptPasswordAutofillSuggestion(
     const base::string16& username) {
 }
 
+void TestAutofillDriver::RendererShouldPreviewPassword(
+      const base::string16& username) {
+}
+
 void TestAutofillDriver::RendererShouldClearFilledForm() {
 }