Added a help link for known chrome policies to about:policy page.

Bug: 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I2da580e882b4e6d9bfd6e30a26553cd3b2bca8d1
Reviewed-on: https://chromium-review.googlesource.com/636188
Commit-Queue: Anton Urusov <[email protected]>
Reviewed-by: Julian Pastarmov <[email protected]>
Reviewed-by: Owen Min <[email protected]>
Reviewed-by: Tommy Li <[email protected]>
Cr-Commit-Position: refs/heads/master@{#499712}
diff --git a/chrome/browser/ui/webui/policy_ui.cc b/chrome/browser/ui/webui/policy_ui.cc
index 855530d..9642a7c 100644
--- a/chrome/browser/ui/webui/policy_ui.cc
+++ b/chrome/browser/ui/webui/policy_ui.cc
@@ -48,6 +48,7 @@
                              IDS_POLICY_SHOW_EXPANDED_VALUE);
   source->AddLocalizedString("hideExpandedValue",
                              IDS_POLICY_HIDE_EXPANDED_VALUE);
+  source->AddLocalizedString("policyLearnMore", IDS_POLICY_LEARN_MORE);
   // Add required resources.
 #if !defined(OS_ANDROID)
   source->AddResourcePath("policy_common.css", IDR_POLICY_COMMON_CSS);