Bug 1465685 - Add login_form probe for Savant Shield study; r=MattN

This probe will register and record (for the duration of the study only):
* When a login form is loaded
* When a login form is submitted (excluding the case from unresolved bug 1287202)

The login_form probe has an 'extra' field called 'flow_id'. This value associates actions that occur in the same tab.

It should be noted that for several reasons, we should expect a higher than 1:1 ratio between 'load' and 'submit' events:
* Some sites, like Google and Amazon, have a two-step login process, and each step fires its own 'load' event. Only the second step fires a 'submit' event.
* Some sites, like Facebook and Twitter, fire multiple 'load' events on the same page.
* A common pattern for unsuccessful logins is for the site to redirect to a page with a login form. This would be a 'load' --> 'submit' --> 'load' series.
* Unlike 'load', the 'submit' event fires only when the Password Manager is enabled and the user is in a non-private window. 'Load' events will have a 'canRecordSubmit' key in the 'extra' field which will be true if a submit event for that form can be recorded.

MozReview-Commit-ID: LOMDSN6tgRV

--HG--
extra : rebase_source : d88dbf2ad97892e14c6a9378cae2559af9c40b92

browser/components/nsBrowserGlue.js

@@ -230,6 +230,7 @@ const listeners = {
     "RemoteLogins:insecureLoginFormPresent": ["LoginManagerParent"],
     // For Savant Shield study, bug 1465685. Study on desktop only.
     "LoginStats:LoginFillSuccessful": ["LoginManagerParent"],
+    "LoginStats:LoginEncountered": ["LoginManagerParent"],
     // PLEASE KEEP THIS LIST IN SYNC WITH THE MOBILE LISTENERS IN BrowserCLH.js
     "WCCR:registerProtocolHandler": ["Feeds"],
     "WCCR:registerContentHandler": ["Feeds"],

toolkit/components/passwordmgr/LoginManagerContent.jsm

@@ -438,8 +438,14 @@ var LoginManagerContent = {
   _fetchLoginsFromParentAndFillForm(form, window) {
     this._detectInsecureFormLikes(window);
 
+    const isPrivateWindow = PrivateBrowsingUtils.isContentWindowPrivate(window);
+
     let messageManager = messageManagerFromWindow(window);
-    messageManager.sendAsyncMessage("LoginStats:LoginEncountered");
+    messageManager.sendAsyncMessage("LoginStats:LoginEncountered",
+                                    {
+                                      isPrivateWindow,
+                                      isPwmgrEnabled: gEnabled,
+                                    });
 
     if (!gEnabled) {
       return;

toolkit/components/passwordmgr/LoginManagerParent.jsm

@@ -94,6 +94,13 @@ var LoginManagerParent = {
                           data.oldPasswordField,
                           msg.objects.openerTopWindow,
                           msg.target);
+
+        const flow_id = msg.target.ownerGlobal.gBrowser.getTabForBrowser(msg.target).linkedPanel;
+        Services.telemetry.recordEvent("savant", "login_form", "submit", null,
+                                      {
+                                        subcategory: "encounter",
+                                        flow_id,
+                                      });
         break;
       }
 
@@ -122,6 +129,18 @@ var LoginManagerParent = {
                                       });
         break;
       }
+
+      case "LoginStats:LoginEncountered": {
+        const canRecordSubmit = (!data.isPrivateWindow && data.isPwmgrEnabled).toString();
+        const flow_id = msg.target.ownerGlobal.gBrowser.getTabForBrowser(msg.target).linkedPanel;
+        Services.telemetry.recordEvent("savant", "login_form", "load", null,
+                                      {
+                                        subcategory: "encounter",
+                                        flow_id,
+                                        canRecordSubmit,
+                                      });
+        break;
+      }
     }
 
     return undefined;

toolkit/components/telemetry/Events.yaml

@@ -255,6 +255,22 @@ savant:
     extra_keys:
       subcategory: The broad event category for this probe. E.g. navigation
       flow_id: A tab identifier to associate events occuring in the same tab
+  login_form:
+    objects: ["load", "submit"]
+    release_channel_collection: opt-out
+    record_in_processes: ["main"]
+    description: >
+      A login form has been loaded or submitted. Login form submit events only
+      fire in non-private windows with Password Manager enabled.
+    bug_numbers: [1457226, 1465685]
+    notification_emails:
+      - "bdanforth@mozilla.com"
+      - "shong@mozilla.com"
+    expiry_version: "65"
+    extra_keys:
+      subcategory: The broad event category for this probe. E.g. navigation
+      flow_id: A tab identifier to associate events occuring in the same tab
+      canRecordSubmit: True if a login form loads in a non-private window with Password Manager enabled.
 
 # This category contains event entries used for Telemetry tests.
 # They will not be sent out with any pings.