weblayer: build weblayer_shell on android too

BUG=none
TEST=none

Change-Id: Id73562a714c9a05e138558b2c4535ca98378b01b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1774208
Auto-Submit: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Cr-Commit-Position: refs/heads/master@{#691479}

BUILD.gn

@@ -195,8 +195,7 @@ group("gn_all") {
     ]
   }
 
-  # TODO: add Android.
-  if (is_win || (is_linux && !is_chromeos)) {
+  if (is_win || (is_linux && !is_chromeos) || is_android) {
     deps += [ "//weblayer/shell:weblayer_shell" ]
   }