Bug 1196017 - Deal with TP turned on globally in about:privatebrowsing. r=paolo

browser/components/privatebrowsing/content/aboutPrivateBrowsing.css

@@ -21,6 +21,9 @@ body[tpEnabled] .showTpDisabled,
 body:not([tpEnabled]) .showTpEnabled {
   display: none !important;
 }
+body[globalTpEnabled] .showGlobalTpDisabled {
+  display: none !important;
+}
 
 @media screen and (min-width: 1200px) and (min-height: 700px) {
   body.private {

browser/components/privatebrowsing/content/aboutPrivateBrowsing.js

@@ -14,18 +14,25 @@ const FAVICON_PRIVACY = "chrome://browser/skin/Privacy-16.png";
 let stringBundle = Services.strings.createBundle(
                      "chrome://browser/locale/aboutPrivateBrowsing.properties");
 
-let prefBranch = Services.prefs.getBranch("privacy.trackingprotection.pbmode.");
+let prefBranch = Services.prefs.getBranch("privacy.trackingprotection.");
 let prefObserver = {
   QueryInterface: XPCOMUtils.generateQI([Ci.nsIObserver,
                                          Ci.nsISupportsWeakReference]),
   observe: function () {
     if (prefBranch.getBoolPref("enabled")) {
+      document.body.setAttribute("globalTpEnabled", "true");
+    } else {
+      document.body.removeAttribute("globalTpEnabled");
+    }
+    if (prefBranch.getBoolPref("pbmode.enabled") ||
+        prefBranch.getBoolPref("enabled")) {
       document.body.setAttribute("tpEnabled", "true");
     } else {
       document.body.removeAttribute("tpEnabled");
     }
   },
 };
+prefBranch.addObserver("pbmode.enabled", prefObserver, true);
 prefBranch.addObserver("enabled", prefObserver, true);
 
 function setFavIcon(url) {

browser/components/privatebrowsing/content/aboutPrivateBrowsing.xhtml

@@ -73,11 +73,11 @@
         <!-- Use text links to implement plain styled buttons without an href. -->
         <label xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
                id="disableTrackingProtection"
-               class="text-link showTpEnabled"
+               class="text-link showTpEnabled showGlobalTpDisabled"
                value="&trackingProtection.disable;"/>
         <label xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
                id="enableTrackingProtection"
-               class="text-link showTpDisabled"
+               class="text-link showTpDisabled showGlobalTpDisabled"
                value="&trackingProtection.enable;"/>
         <p id="tpStartTour"
            class="showTpEnabled"><a id="startTour">&trackingProtection.startTour1;</a></p>