Broaden DEPS for keyboard overlay tests.

Follow up to 0a98cc85

Bug: none
Change-Id: I1295fe4dbf4ae913689b8d2b1bd57e8554483566
Reviewed-on: https://chromium-review.googlesource.com/1138986Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575446}

ash/content/keyboard_overlay/DEPS

@@ -3,6 +3,6 @@ include_rules = [
 ]
 specific_include_rules = {
   ".*test\.cc": [
-    "+content/public/test/test_browser_context.h",
+    "+content/public/test",
   ],
 }