Add HeadlessFocusClient to fix document.hasFocus() issues.

headless/lib/browser/headless_browser_impl.cc

Index: headless/lib/browser/headless_browser_impl.cc
diff --git a/headless/lib/browser/headless_browser_impl.cc b/headless/lib/browser/headless_browser_impl.cc
index e0546b174fa1deaefa8462946423e31578196861..402477b94ff8a1193d9409724bb2704e2f5bac9a 100644
--- a/headless/lib/browser/headless_browser_impl.cc
+++ b/headless/lib/browser/headless_browser_impl.cc
@@ -20,6 +20,7 @@
 #include "headless/lib/browser/headless_web_contents_impl.h"
 #include "headless/lib/headless_content_main_delegate.h"
 #include "ui/aura/env.h"
+#include "ui/aura/test/test_focus_client.h"
 #include "ui/aura/window.h"
 #include "ui/events/devices/device_data_manager.h"
 #include "ui/gfx/geometry/size.h"
@@ -49,7 +50,8 @@ int RunContentMain(
 HeadlessBrowserImpl::HeadlessBrowserImpl(
     const base::Callback<void(HeadlessBrowser*)>& on_start_callback,
     HeadlessBrowser::Options options)
-    : on_start_callback_(on_start_callback),
+    : focus_client_(new aura::test::TestFocusClient()),

[Eric Seckler, 2017/02/22 09:00:04]

Let's get rid of the init here, since you reset it during
PlatformCreateWindow(). (Otherwise, it'd need to be inside an "#if
defined(USE_AURA)".)

[irisu, 2017/02/23 00:02:26]

Done.

+      on_start_callback_(on_start_callback),
       options_(std::move(options)),
       browser_main_parts_(nullptr),
       default_browser_context_(nullptr),