Update history ui and ntp tiles for ephemeral Guest profiles.

Updates ntp_tiles_internals_ui.cc and history_ui.cc  for compatibility
with ephemeral Guest profiles.

This change is behind disabled |EnableEphemeralGuestProfilesOnDesktop|
flag.
Please see go/ephemeral-guest-profiles for more context.

Bug: 1125474
Change-Id: Ib538a3df1d3c547817f57473bd1d3cce85df0299
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2461337Reviewed-by: calamity <calamity@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816072}

chrome/browser/ui/webui/history/history_ui.cc

@@ -120,7 +120,8 @@ content::WebUIDataSource* CreateHistoryUIHTMLSource(Profile* profile) {
   source->AddBoolean("allowDeletingHistory", allow_deleting_history);
 
   source->AddBoolean(kShowMenuPromoKey, !MenuPromoShown(profile));
-  source->AddBoolean("isGuestSession", profile->IsGuestSession());
+  source->AddBoolean("isGuestSession", profile->IsGuestSession() ||
+                                           profile->IsEphemeralGuestProfile());
 
   source->AddBoolean(kIsUserSignedInKey, IsUserSignedIn(profile));
 

chrome/browser/ui/webui/ntp_tiles_internals_ui.cc

@@ -71,7 +71,8 @@ void ChromeNTPTilesInternalsMessageHandlerClient::RegisterMessages() {
 
 bool ChromeNTPTilesInternalsMessageHandlerClient::SupportsNTPTiles() {
   Profile* profile = Profile::FromWebUI(web_ui());
-  return !(profile->IsGuestSession() || profile->IsOffTheRecord());
+  return !(profile->IsGuestSession() || profile->IsEphemeralGuestProfile() ||
+           profile->IsOffTheRecord());
 }
 
 bool ChromeNTPTilesInternalsMessageHandlerClient::DoesSourceExist(