Gamepad: add test support for page visibility behavior

content/renderer/render_thread_impl.h

Index: content/renderer/render_thread_impl.h
diff --git a/content/renderer/render_thread_impl.h b/content/renderer/render_thread_impl.h
index 4afe3ed2b353afed96261c9c259bcb899dbbdf9d..d8d50c8320b3025a4839f6c2347bc9ee1e9d17f5 100644
--- a/content/renderer/render_thread_impl.h
+++ b/content/renderer/render_thread_impl.h
@@ -192,6 +192,11 @@ class CONTENT_EXPORT RenderThreadImpl : public RenderThread,
     layout_test_mode_ = layout_test_mode;
   }
 
+  RendererWebKitPlatformSupportImpl* webkit_platform_support() const {
+    DCHECK(webkit_platform_support_);
+    return webkit_platform_support_.get();
+  }
+
   IPC::ForwardingMessageFilter* compositor_output_surface_filter() const {
     return compositor_output_surface_filter_.get();
   }