Teach PasswordAutofillAgent sometimes match prefixes of usernames

chrome/renderer/autofill/password_autofill_agent_browsertest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/autofill/content/renderer/password_autofill_agent.h"
 
 #include "base/macros.h"
 #include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
@@ skipping 699 matching lines @@
        AutocompletePasswordForReadonlyUsernameMatched) {
   username_element_.SetValue(WebString::FromUTF16(username3_));
   SetElementReadOnly(username_element_, true);
 
   // Filled even though username is not the preferred match.
   SimulateOnFillPasswordForm(fill_data_);
   CheckTextFieldsState(UTF16ToUTF8(username3_), false,
                        UTF16ToUTF8(password3_), true);
 }
 
+// Fill a password field if the stored username is a prefix of username in
+// read-only field.
+TEST_F(PasswordAutofillAgentTest,
+       AutocompletePasswordForReadonlyUsernamePrefixMatched) {
+  base::string16 username_at = username3_ + base::UTF8ToUTF16("@example.com");
+  username_element_.SetValue(WebString::FromUTF16(username_at));
+  SetElementReadOnly(username_element_, true);
+
+  // Filled even though the username in the form is only a proper prefix of the
+  // stored username.
+  SimulateOnFillPasswordForm(fill_data_);
+  CheckTextFieldsState(UTF16ToUTF8(username_at), false, UTF16ToUTF8(password3_),
+                       true);
+}
+
+// Do not fill a password field if the stored username is a prefix without @
+// of username in read-only field.
+TEST_F(PasswordAutofillAgentTest,
+       DontAutocompletePasswordForReadonlyUsernamePrefixMatched) {
+  base::string16 prefilled_username =
+      username3_ + base::UTF8ToUTF16("example.com");
+  username_element_.SetValue(WebString::FromUTF16(prefilled_username));
+  SetElementReadOnly(username_element_, true);
+
+  // Filled even though the username in the form is only a proper prefix of the
+  // stored username.
+  SimulateOnFillPasswordForm(fill_data_);
+  CheckTextFieldsState(UTF16ToUTF8(prefilled_username), false, std::string(),
+                       false);
+}
+
+// Do not fill a password field if the field isn't readonly despite the stored
+// username is a prefix without @ of username in read-only field.
+TEST_F(
+    PasswordAutofillAgentTest,
+    DontAutocompletePasswordForNotReadonlyUsernameFieldEvenWhenPrefixMatched) {
+  base::string16 prefilled_username =
+      username3_ + base::UTF8ToUTF16("@example.com");
+  username_element_.SetValue(WebString::FromUTF16(prefilled_username));
+
+  // Filled even though the username in the form is only a proper prefix of the
+  // stored username.
+  SimulateOnFillPasswordForm(fill_data_);
+  CheckTextFieldsState(UTF16ToUTF8(prefilled_username), false, std::string(),
+                       false);
+}
+
 // If a username field is empty and readonly, don't autofill.
 TEST_F(PasswordAutofillAgentTest,
        NoAutocompletePasswordForReadonlyUsernameUnmatched) {
   username_element_.SetValue(WebString::FromUTF8(""));
   SetElementReadOnly(username_element_, true);
 
   SimulateOnFillPasswordForm(fill_data_);
   CheckTextFieldsState(std::string(), false, std::string(), false);
 }
 
@@ skipping 2245 matching lines @@
   // Repeatedly occurring AJAX events without removing the input elements
   // shouldn't be treated as a password submission.
   password_autofill_agent_->AJAXSucceeded();
   base::RunLoop().RunUntilIdle();
 
   ASSERT_FALSE(fake_driver_.called_password_form_submitted());
   ASSERT_FALSE(static_cast<bool>(fake_driver_.password_form_submitted()));
 }
 
 }  // namespace autofill