Teach PasswordAutofillAgent sometimes match prefixes of usernames

components/autofill/content/renderer/password_autofill_agent.cc

Index: components/autofill/content/renderer/password_autofill_agent.cc
diff --git a/components/autofill/content/renderer/password_autofill_agent.cc b/components/autofill/content/renderer/password_autofill_agent.cc
index 642f6ff863bf131e0268361f5924545bc5ba5fbc..f1505962828835b6c27eff934458875a02b44563 100644
--- a/components/autofill/content/renderer/password_autofill_agent.cc
+++ b/components/autofill/content/renderer/password_autofill_agent.cc
@@ -267,13 +267,14 @@ bool IsElementEditable(const blink::WebInputElement& element) {
   return element.IsEnabled() && !element.IsReadOnly();
 }
 
-bool DoUsernamesMatch(const base::string16& username1,
-                      const base::string16& username2,
+bool DoUsernamesMatch(const base::string16& potential_suggestion,
+                      const base::string16& current_username,
                       bool exact_match) {
-  if (exact_match)
-    return username1 == username2;
-  return FieldIsSuggestionSubstringStartingOnTokenBoundary(username1, username2,
-                                                           true);
+  bool match = (potential_suggestion == current_username);
+  return exact_match
+             ? match
+             : (match || IsPrefixStartingOnTokenBoundary(
+                             current_username, potential_suggestion, true));

[dvadym, 2017/06/01 12:15:56]

As far as I understand the main use case is emails, so it looks that we can
compare Case Insensitive. And probably even remove |case_sensitive| argument in
IsPrefixStartingOnTokenBoundary. WDYT?

[melandory, 2017/06/12 14:56:12]

My motivation was that since currently gmail suffers from this bug and it teats
Example@gmail.com and example@gmail.com as one account, we can do the same. But
either way is fine by me.

[vabr (Chromium), 2017/06/12 18:56:58]

Currently case sensitive equality is required. Let's keep using case sensitive
comparison also for the prefix, as for not to introduce two changes with one CL.
If we find out case sensitivity is an issue, we can change that in a separate
CL.

 }
 
 // Returns |true| if the given element is editable. Otherwise, returns |false|.
@@ -358,6 +359,51 @@ void UpdateFieldValueAndPropertiesMaskMap(
   }
 }
 
+void FindMatchesByUsername(const PasswordFormFillData& fill_data,
+                           const base::string16& current_username,
+                           bool exact_username_match,
+                           RendererSavePasswordProgressLogger* logger,
+                           base::string16* username,
+                           base::string16* password) {
+  // Look for any suitable matches to current field text.
+  if (DoUsernamesMatch(fill_data.username_field.value, current_username,
+                       exact_username_match)) {
+    *username = fill_data.username_field.value;
+    *password = fill_data.password_field.value;
+    if (logger)
+      logger->LogMessage(Logger::STRING_USERNAMES_MATCH);
+  } else {
+    // Scan additional logins for a match.
+    for (const auto& it : fill_data.additional_logins) {
+      if (DoUsernamesMatch(it.first, current_username, exact_username_match)) {
+        *username = it.first;
+        *password = it.second.password;
+        break;
+      }
+    }
+    if (logger) {
+      logger->LogBoolean(Logger::STRING_MATCH_IN_ADDITIONAL,
+                         !(username->empty() && password->empty()));
+    }
+
+    // Check possible usernames.
+    if (username->empty() && password->empty()) {
+      for (const auto& it : fill_data.other_possible_usernames) {
+        for (size_t i = 0; i < it.second.size(); ++i) {
+          if (DoUsernamesMatch(it.second[i], current_username,
+                               exact_username_match)) {
+            *username = it.second[i];
+            *password = it.first.password;
+            break;
+          }
+        }
+        if (!username->empty() && !password->empty())
+          break;
+      }
+    }
+  }
+}
+
 // This function attempts to fill |username_element| and |password_element|
 // with values from |fill_data|. The |password_element| will only have the
 // suggestedValue set, and will be registered for copying that to the real
@@ -389,43 +435,9 @@ bool FillUserNameAndPassword(
   base::string16 username;
   base::string16 password;
 
-  // Look for any suitable matches to current field text.
-  if (DoUsernamesMatch(fill_data.username_field.value, current_username,
-                       exact_username_match)) {
-    username = fill_data.username_field.value;
-    password = fill_data.password_field.value;
-    if (logger)
-      logger->LogMessage(Logger::STRING_USERNAMES_MATCH);
-  } else {
-    // Scan additional logins for a match.
-    for (const auto& it : fill_data.additional_logins) {
-      if (DoUsernamesMatch(it.first, current_username, exact_username_match)) {
-        username = it.first;
-        password = it.second.password;
-        break;
-      }
-    }
-    if (logger) {
-      logger->LogBoolean(Logger::STRING_MATCH_IN_ADDITIONAL,
-                         !(username.empty() && password.empty()));
-    }
+  FindMatchesByUsername(fill_data, current_username, exact_username_match,
+                        logger, &username, &password);
 
-    // Check possible usernames.
-    if (username.empty() && password.empty()) {
-      for (const auto& it : fill_data.other_possible_usernames) {
-        for (size_t i = 0; i < it.second.size(); ++i) {
-          if (DoUsernamesMatch(
-                  it.second[i], current_username, exact_username_match)) {
-            username = it.second[i];
-            password = it.first.password;
-            break;
-          }
-        }
-        if (!username.empty() && !password.empty())
-          break;
-      }
-    }
-  }
   if (password.empty())
     return false;
 
@@ -447,9 +459,10 @@ bool FillUserNameAndPassword(
       form_util::PreviewSuggestion(username, current_username,
                                    username_element);
     }
-  } else if (current_username != username) {
+  } else if (exact_username_match && current_username != username) {
     // If the username can't be filled and it doesn't match a saved password
-    // as is, don't autofill a password.
+    // as is, autofill the password only in case the username element id read
+    // only.
     return false;
   }
 
@@ -535,12 +548,15 @@ bool FillFormOnPasswordReceived(
         blink::WebString::FromUTF16(fill_data.username_field.value));
   }
 
-  // Fill if we have an exact match for the username. Note that this sets
-  // username to autofilled.
+  bool exact_username_match =
+      username_element.IsNull() || IsElementEditable(username_element);
+  // User the exact match for the editable username fields and allow prefix
+  // match for read-only username fields.
+  // Note that this sets username to autofilled.
   return FillUserNameAndPassword(
-      &username_element, &password_element, fill_data,
-      true /* exact_username_match */, false /* set_selection */,
-      field_value_and_properties_map, registration_callback, logger);
+      &username_element, &password_element, fill_data, exact_username_match,
+      false /* set_selection */, field_value_and_properties_map,
+      registration_callback, logger);
 }
 
 // Annotate |forms| with form and field signatures as HTML attributes.