Bug 1303682 - Add deprecation warning before removing 'referrer' directive from CSP. r=ckerschb

dom/locales/en-US/chrome/security/csp.properties

@@ -77,6 +77,9 @@ ignoringDirectiveWithNoValues = Ignoring ‘%1$S’ since it does not contain an
 # LOCALIZATION NOTE (ignoringReportOnlyDirective):
 # %1$S is the directive that is ignored in report-only mode.
 ignoringReportOnlyDirective = Ignoring sandbox directive when delivered in a report-only policy ‘%1$S’
+# LOCALIZATION NOTE (deprecatedReferrerDirective):
+# %1$S is the value of the deprecated Referrer Directive.
+deprecatedReferrerDirective = Referrer Directive ‘%1$S’ has been deprecated. Please use the Referrer-Policy header instead.
 
 # CSP Errors:
 # LOCALIZATION NOTE (couldntParseInvalidSource):

dom/security/nsCSPParser.cpp

@@ -865,6 +865,11 @@ nsCSPParser::referrerDirectiveValue(nsCSPDirective* aDir)
     return;
   }
 
+  //referrer-directive deprecation warning
+  const char16_t* params[] = { mCurDir[1].get() };
+  logWarningErrorToConsole(nsIScriptError::warningFlag, "deprecatedReferrerDirective",
+                             params, ArrayLength(params));
+
   // the referrer policy is valid, so go ahead and use it.
   mPolicy->setReferrerPolicy(&mCurDir[1]);
   mPolicy->addDirective(aDir);