Enable WebUSB through the Experimental Framework.

content/renderer/render_frame_impl.cc

Index: content/renderer/render_frame_impl.cc
diff --git a/content/renderer/render_frame_impl.cc b/content/renderer/render_frame_impl.cc
index c16d78605ef327d2e38684890f0379344ddbab4b..07d248657d1d02823b2c1c2e2723f581555e65fa 100644
--- a/content/renderer/render_frame_impl.cc
+++ b/content/renderer/render_frame_impl.cc
@@ -63,6 +63,7 @@
 #include "content/public/common/bindings_policy.h"
 #include "content/public/common/browser_side_navigation_policy.h"
 #include "content/public/common/content_constants.h"
+#include "content/public/common/content_features.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/context_menu_params.h"
 #include "content/public/common/isolated_world_ids.h"
@@ -4285,6 +4286,9 @@ blink::WebBluetooth* RenderFrameImpl::bluetooth() {
 }
 
 blink::WebUSBClient* RenderFrameImpl::usbClient() {
+  if (!base::FeatureList::IsEnabled(features::kWebUsb))
+    return nullptr;
+
   if (!usb_client_)
     usb_client_.reset(new WebUSBClientImpl(GetServiceRegistry()));