[components] Autofill: Show fallback if login is empty.

android-components/components/feature/autofill/src/main/java/mozilla/components/feature/autofill/handler/FillRequestHandler.kt

@@ -105,9 +105,9 @@ private fun createLoginsResponse(
 
     logins.forEach { login ->
         val usernamePresentation = RemoteViews(context.packageName, android.R.layout.simple_list_item_1)
-        usernamePresentation.setTextViewText(android.R.id.text1, login.username)
+        usernamePresentation.setTextViewText(android.R.id.text1, login.usernamePresentationOrFallback(context))
         val passwordPresentation = RemoteViews(context.packageName, android.R.layout.simple_list_item_1)
-        passwordPresentation.setTextViewText(android.R.id.text1, "Password for ${login.username}")
+        passwordPresentation.setTextViewText(android.R.id.text1, login.passwordPresentation(context))
 
         val dataset = Dataset.Builder()
 
@@ -132,3 +132,18 @@ private fun createLoginsResponse(
 
     return builder.build()
 }
+
+private fun Login.usernamePresentationOrFallback(context: Context): String {
+    return if (username.isNotEmpty()) {
+        username
+    } else {
+        context.getString(R.string.mozac_feature_autofill_popup_no_username)
+    }
+}
+
+private fun Login.passwordPresentation(context: Context): String {
+    return context.getString(
+        R.string.mozac_feature_autofill_popup_password,
+        usernamePresentationOrFallback(context)
+    )
+}

android-components/components/feature/autofill/src/main/res/values/strings.xml

@@ -7,4 +7,13 @@
      a username or password can be autofilled for the highlighted text field. %1$s will be replaced
      with the name of the browser application (e.g. Firefox) -->
     <string name="mozac_feature_autofill_popup_unlock_application">Unlock %1$s</string>
+
+    <!-- Autofill: Text shown in popup in third-party app if we found a matching account, but no
+    username is saved (e.g. we only have a password). This text will be shown in place where otherwise
+    the username would be displayed. -->
+    <string name="mozac_feature_autofill_popup_no_username">(No username)</string>
+
+    <!-- Autofill: Text shown in popup in third-party app to autofill the password for an account.
+    %1$s will be replaced with the login/username of the account. -->
+    <string name="mozac_feature_autofill_popup_password">Password for %1$s</string>
 </resources>

android-components/samples/browser/src/main/java/org/mozilla/samples/browser/storage/DummyLoginsStorage.kt

@@ -22,6 +22,12 @@ class DummyLoginsStorage : LoginsStorage {
             origin = "twitter.com",
             username = "NotAnAccount",
             password = "NotReallyAPassword"
+        ),
+        Login(
+            guid = "8034a37f-5f9e-4136-95b2-e0293116b322",
+            origin = "twitter.com",
+            username = "",
+            password = "NotReallyAPassword"
         )
     )