Add a notice about other forms of browsing history to the History WebUI.

components/history_strings.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <grit-part>
 
   <!-- History UI -->
   <message name="IDS_HISTORY_ACTION_MENU_DESCRIPTION" desc="Text used to identify the history entry drop-down menu for screen readers">
     Actions
   </message>
   <message name="IDS_HISTORY_BLOCKED_VISIT_TEXT" desc="Text that describes an attempted visit.">
     Blocked attempt <ph name="BEGIN_LINK">&lt;a target="_top" href="$1" id="$2"&gt;</ph> to visit a page on <ph name="DOMAIN">$3<ex>google.com</ex></ph><ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph>.
   </message>
@@ skipping 35 matching lines @@
   <message name="IDS_HISTORY_FILTER_BLOCKED" desc="Text that shows that an entry is blocked.">
     Blocked
   </message>
   <message name="IDS_HISTORY_FOUND_SEARCH_RESULTS" desc="Message shown when zero or multiple search results are found.">
     Found <ph name="NUMBER_OF_RESULTS">$1</ph> <ph name="SEARCH_RESULTS"><ex>search results</ex>$2</ph> for '<ph name="SEARCH_STRING">$3</ph>'.
   </message>
   <message name="IDS_HISTORY_GROUP_BY_DOMAIN_LABEL" desc="Label for the checkbox that toggles the mode to group history visits by domain.">
     Group domains
   </message>
   <message name="IDS_HISTORY_HAS_SYNCED_RESULTS" desc="The notification at the top of the history page indicating that it is showing visits synced from other devices.">
-    Showing history from your signed-in devices. <ph name="BEGIN_LINK">&lt;a href="https://support.google.com/chrome/?p=sync_history&amp;hl=[GRITLANGCODE]"&gt;</ph>Learn more<ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph>
+    Showing history from your signed-in devices. <ph name="BEGIN_LINK">&lt;a href="https://support.google.com/chrome/?p=sync_history&amp;hl=[GRITLANGCODE]"&gt;</ph>Learn more<ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph>.
+  </message>
+  <message name="IDS_HISTORY_OTHER_FORMS_OF_HISTORY" desc="The notification at the top of the history page indicating that deleting Chrome browsing history will not delete other forms of history stored at Google My Activity.">
+    Your Google Account may have other forms of browsing history at <ph name="BEGIN_LINK">&lt;a target="_blank" href="$1"&gt;</ph>history.google.com<ph name="END_LINK">&lt;/a&gt;</ph>.
   </message>
   <message name="IDS_HISTORY_IN_CONTENT_PACK" desc="Text that shows that an entry is in a content pack.">
     In content pack
   </message>
   <message name="IDS_HISTORY_INTERVAL" desc="A history interval shown in the title. The dates are already localized strings.">
     <ph name="START_DATE">$1<ex>Wednesday, Aug. 1, 2012</ex></ph> to <ph name="END_DATE">$2<ex>Thursday, Aug. 30, 2012</ex></ph>
   </message>
   <message name="IDS_HISTORY_LOADING" desc="Text shown when we're loading the user's history">
     Loading...
   </message>
   <message name="IDS_HISTORY_MORE_FROM_SITE" desc="Command in the history entry drop-down menu. Shows more history entries from the same site.">
     More from this site
   </message>
   <message name="IDS_HISTORY_NEWER" desc="HTML text shown as page navigation tool to take the user back to the more recent page">
     Newer
   </message>
   <message name="IDS_HISTORY_NEWEST" desc="HTML text shown as page navigation tool to take the user to the top of their history">
     Newest
   </message>
   <message name="IDS_HISTORY_NO_RESULTS" desc="Text shown when no history entries are found.">
     No history entries found.
   </message>
   <message name="IDS_HISTORY_NO_SEARCH_RESULTS" desc="Text shown when no history search results have been found">
     No search results found.
   </message>
   <message name="IDS_HISTORY_NO_SYNCED_RESULTS" desc="The notification at the top of the history page indicating that it does not include visits from other devices.">
-    Showing history from this device. <ph name="BEGIN_LINK">&lt;a href="https://support.google.com/chrome/?p=sync_history&amp;hl=[GRITLANGCODE]"&gt;</ph>Learn more<ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph>
+    Showing history from this device. <ph name="BEGIN_LINK">&lt;a href="https://support.google.com/chrome/?p=sync_history&amp;hl=[GRITLANGCODE]"&gt;</ph>Learn more<ph name="END_LINK">&lt;/a&gt;<ex>&lt;/a&gt;</ex></ph>.
   </message>
   <message name="IDS_HISTORY_NUMBER_VISITS" desc="Format string for the number of visits of a site.">
     (<ph name="NUMBER_VISITS">$1<ex>3</ex></ph>)
   </message>
   <message name="IDS_HISTORY_OLDER" desc="HTML text shown as page navigation tool to take the user forward to their older history">
     Older
   </message>
   <message name="IDS_HISTORY_OPEN_CLEAR_BROWSING_DATA_DIALOG" desc="Title of the button that will open the clear browsing data dialog.">
     Clear browsing data...
   </message>
@@ skipping 65 matching lines @@
     Show Full History
   </message>
   <message name="IDS_HISTORY_TITLE" desc="Title for the history tab.">
     History
   </message>
   <message name="IDS_HISTORY_UNKNOWN_DEVICE" desc="On the dropdown menu for a history entry, the text that is shown instead of a device name, when the device name is not known.">
     Unknown device
   </message>
 
 </grit-part>