Update taskbar decorator for ephemeral Guest profiles.

Taskbar decordator update is triggered for ephemeral Guest profiles
similar to old Guest profiles.

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

Bug: 1125474
Change-Id: I543b8966cbcf79e080ad2d537c0b4cd4455754ee
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2460901Reviewed-by: David Roger <droger@chromium.org>
Commit-Queue: Ramin Halavati <rhalavati@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816057}

chrome/browser/taskbar/taskbar_decorator_win.cc

@@ -184,7 +184,7 @@ void DrawTaskbarDecoration(gfx::NativeWindow window, const gfx::Image* image) {
 }
 
 void UpdateTaskbarDecoration(Profile* profile, gfx::NativeWindow window) {
-  if (profile->IsGuestSession() ||
+  if (profile->IsGuestSession() || profile->IsEphemeralGuestProfile() ||
       // Browser process and profile manager may be null in tests.
       (g_browser_process && g_browser_process->profile_manager() &&
        g_browser_process->profile_manager()