Merge pull request #58 from w3c/history

Editorial: Add Contacts API history note

index.bs

@@ -443,3 +443,21 @@ interface ContactsManager {
   * The UI MUST provide an a way for users to indicate that they are done selecting, in which case
     remove the UI and return a [=list=] of the selected contacts as [=user contacts=].
 </div>
+
+# Acknowledgments
+
+There has been multiple earlier attempts to standardize a Contacts API for the web and this
+API strives to learn from this rich history. Earlier attempts include Mozilla's
+[Contacts API](https://wiki.mozilla.org/WebAPI/ContactsAPI),
+[Contacts API](https://lists.w3.org/Archives/Public/public-device-apis/2009Apr/att-0001/contacts.html)
+W3C Member submission and standardization efforts by W3C Working Groups:
+[Contacts API](https://www.w3.org/TR/2010/WD-contacts-api-20100121/),
+[Pick Contacts Intent](https://www.w3.org/TR/2014/NOTE-contacts-api-20140114/), and
+[Contacts Manager API](https://www.w3.org/TR/2015/NOTE-contacts-manager-api-20150602/).
+The Contact Picker API differs in its approach to privacy, which was the main emphasis of the API
+when it was designed. Unlike previous attempts which allow for perpetual access after granted
+permission, or include a vague privacy model, this spec enforces UI restrictions which give users
+full control over shared data and limit abuse. For example, a picker model is enforced where the
+user always acts as an intermediary of the shared contact info with full control every time
+contacts are requested. For more historical context, please refer to the Status of the Document
+sections of the earlier attempts.