Add missing #includes of browser_test.h.

This is a step towards doing full IWYU of browser_test.h, which will
have other benefits.

Completely mechanical and already R+ed as part of r765923.

Tbr: sky
Bug: none
Change-Id: Icb7ab728098a6cf29c0920da4b524e96a7c024c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2186411
Commit-Queue: Peter Kasting <pkasting@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#766361}
diff --git a/chrome/browser/global_keyboard_shortcuts_mac_browsertest.mm b/chrome/browser/global_keyboard_shortcuts_mac_browsertest.mm
index 5428228..f9e083c 100644
--- a/chrome/browser/global_keyboard_shortcuts_mac_browsertest.mm
+++ b/chrome/browser/global_keyboard_shortcuts_mac_browsertest.mm
@@ -19,6 +19,7 @@
 #include "chrome/test/base/interactive_test_utils.h"
 #include "chrome/test/base/ui_test_utils.h"
 #include "components/omnibox/browser/omnibox_view.h"
+#include "content/public/test/browser_test.h"
 #include "content/public/test/test_navigation_observer.h"
 #include "content/public/test/test_utils.h"
 #include "ui/events/event_constants.h"