Bug 1555231 - Part 2: Add strings for protections panel footer section. r=nhnt11,flod

This patch adds two strings, one for the blocked tracker counter and
another for the tooltip.

Differential Revision: https://phabricator.services.mozilla.com/D39693

--HG--
extra : moz-landing-system : lando

browser/locales/en-US/chrome/browser/browser.properties

@@ -647,6 +647,20 @@ protections.notBlocking.crossSiteTrackingCookies.title=Not Blocking Cross-Site T
 protections.notBlocking.trackingContent.title=Not Blocking Tracking Content
 protections.notBlocking.socialMediaTrackers.title=Not Blocking Social Media Trackers
 
+# Footer section in the Protections Panel
+# LOCALIZATION NOTE (protections.footer.blockedTrackerCounter.description,
+# protections.footer.blockedTrackerCounter.tooltip):
+#   This text indicates the total number of trackers blocked on all sites. In
+#   its tooltip, we show the date when we started counting this number.
+# LOCALIZATION NOTE (protections.footer.blockedTrackerCounter.description):
+#   Semicolon-separated list of plural forms.
+#   See: http://developer.mozilla.org/en/docs/Localization_and_Plurals
+#   Replacement for #1 is a locale-string converted positive integer.
+protections.footer.blockedTrackerCounter.description=1 Blocked;#1 Blocked
+# LOCALIZATION NOTE (protections.footer.blockedTrackerCounter.tooltip):
+#   %S is the date on which we started counting (e.g., July 17, 2019).
+protections.footer.blockedTrackerCounter.tooltip=Since %S
+
 # Edit Bookmark UI
 editBookmarkPanel.newBookmarkTitle=New Bookmark
 editBookmarkPanel.editBookmarkTitle=Edit This Bookmark