Move IDS_LEARN_MORE to components_strings.grd

To componentize sad_tab related code, move IDS_LEARN_MORE to outside of chrome.

BUG=402485
[email protected] for include fix under chrome/browser

Review URL: https://codereview.chromium.org/530963002

Cr-Commit-Position: refs/heads/master@{#292908}
diff --git a/components/components_strings.grd b/components/components_strings.grd
index 9a01629..0501bdb 100644
--- a/components/components_strings.grd
+++ b/components/components_strings.grd
@@ -175,6 +175,11 @@
       <part file="pdf_strings.grdp" />
       <part file="policy_strings.grdp" />
       <part file="translate_strings.grdp" />
+
+      <!-- Generic terms -->
+      <message name="IDS_LEARN_MORE" desc="Learn more text">
+        Learn more
+      </message>
     </messages>
   </release>
 </grit>