bug 897121. Move handling of DNT pref to prefsFlyout.js. Correctly (hopefully :) deal with the various pref values that are possible. r=rsilveira

browser/metro/base/content/browser.xul

@@ -721,11 +721,11 @@
         <setting pref="app.crashreporter.autosubmit" type="bool" title="&optionsHeader.reporting.crashes.label;" oncommand="BrowserUI.crashReportingPrefChanged(this.value);"/>
       </settings>
       <settings id="prefs-telemetry" label="&optionsHeader.telemetry.title;">
-        <setting pref="toolkit.telemetry.enabled" type="bool" title="&optionsHeader.telemetry.label;" oncommand="FlyoutPanelsUI.PrefsFlyoutPanel.onTelemetryPreferenceChanged(this.value);"/>
+        <setting pref="toolkit.telemetry.enabled" type="bool" title="&optionsHeader.telemetry.label;"/>
       </settings>
       <settings id="prefs-dnt" label="&doNotTrack.title;">
         <description>&doNotTrack.desc;</description>
-        <setting id="prefs-dnt-value" pref="privacy.donottrackheader.value" onpreferencechanged="FlyoutPanelsUI.PrefsFlyoutPanel.onDNTPreferenceChanged();" type="radio" >
+        <setting id="prefs-dnt-value" pref="privacy.donottrackheader.value" type="radio" >
           <radiogroup id="prefs-dnt-options">
             <radio id="prefs-dnt-notrack" label="&doNotTrack.options.trackingNotOkay;" value="1"/>
             <radio id="prefs-dnt-nopref" label="&doNotTrack.options.noPreference;" value="-1"/>

browser/metro/base/content/flyoutpanels/FlyoutPanelsUI.js

@@ -52,7 +52,7 @@ let FlyoutPanelsUI = {
     }
 
     this._currentFlyout = this[aToShow];
-    if (this._currentFlyout.show) {
+    if (this._currentFlyout._show) {
       this._currentFlyout._show();
     } else {
       this._currentFlyout._topmostElement.show();

browser/metro/base/content/flyoutpanels/PrefsFlyoutPanel.js

@@ -22,8 +22,6 @@ let PrefsFlyoutPanel = {
     this._elements = {};
     [
       ['PrefsFlyoutPanel',  'prefs-flyoutpanel'],
-      ['dntNoPref',    'prefs-dnt-nopref'],
-      ['telemetryPref','prefs-telemetry'],
     ].forEach(function(aElement) {
       let [name, id] = aElement;
       XPCOMUtils.defineLazyGetter(self._elements, name, function() {
@@ -31,6 +29,7 @@ let PrefsFlyoutPanel = {
       });
     });
 
+    this._prefObserver(null, null, "privacy.donottrackheader.value");
     this._topmostElement = this._elements.PrefsFlyoutPanel;
   },
 
@@ -38,19 +37,50 @@ let PrefsFlyoutPanel = {
     if (!this._hasShown) {
       SanitizeUI.init();
       this._hasShown = true;
+
+      Services.prefs.addObserver("privacy.donottrackheader.value",
+                                 this._prefObserver,
+                                 false);
+      Services.prefs.addObserver("privacy.donottrackheader.enabled",
+                                 this._prefObserver,
+                                 false);
     }
 
-    this._elements.PrefsFlyoutPanel.show();
+    this._topmostElement.show();
   },
 
-  onDNTPreferenceChanged: function onDNTPreferenceChanged() {
-    let selected = this._elements.dntNoPref.selected;
+  _prefObserver: function(subject, topic, data) {
+    let value = -1;
+    try {
+      value = Services.prefs.getIntPref("privacy.donottrackheader.value");
+    } catch(e) {
+    }
 
-    // When "tell sites nothing about my preferences" is selected, disable do not track.
-    Services.prefs.setBoolPref("privacy.donottrackheader.enabled", !selected);
+    let isEnabled = Services.prefs.getBoolPref("privacy.donottrackheader.enabled");
+
+    switch (data) {
+      case "privacy.donottrackheader.value":
+        // If the user has selected to explicitly tell sites that tracking
+        // is OK, or if the user has selected to explicitly tell sites that
+        // tracking is NOT OK, we must enable sending the dnt header
+        if (((1 == value) || (0 == value)) && !isEnabled) {
+          Services.prefs.setBoolPref('privacy.donottrackheader.enabled', true);
+        }
+
+        // If the user has made no selection about whether tracking
+        // is OK or not, we must diable the dnt header
+        if (((1 != value) && (0 != value)) && isEnabled) {
+          Services.prefs.setBoolPref('privacy.donottrackheader.enabled', false);
+        }
+        break;
+
+      case "privacy.donottrackheader.enabled":
+        // If someone or something modifies this pref, we should update the
+        // other pref as well so our UI doesn't give false information
+        if (((1 == value) || (0 == value)) && !isEnabled) {
+          Services.prefs.setIntPref('privacy.donottrackheader.value', -1);
+        }
+        break;
+    }
   },
-
-  onTelemetryPreferenceChanged: function onTelemetryPreferenceChanged(aBool) {
-    Services.prefs.setBoolPref("toolkit.telemetry.enabled", aBool);
-  }
 };