Disable WebUSB chooser service on chrome extension

chrome/browser/chrome_content_browser_client.cc

Index: chrome/browser/chrome_content_browser_client.cc
diff --git a/chrome/browser/chrome_content_browser_client.cc b/chrome/browser/chrome_content_browser_client.cc
index a00041a46e26985515246c927dfbd4e07b086f48..03bc2dc0e1e819de56b839dd5fbc566ca3ceb107 100644
--- a/chrome/browser/chrome_content_browser_client.cc
+++ b/chrome/browser/chrome_content_browser_client.cc
@@ -2774,10 +2774,17 @@ void ChromeContentBrowserClient::RegisterRenderFrameMojoServices(
     content::ServiceRegistry* registry,
     content::RenderFrameHost* render_frame_host) {
   // WebUSB is an experimental web API. It will only work if the experiment
-  // is enabled and WebUSB feature is enabled.
+  // is enabled and WebUSB feature is enabled and it is not used from chrome
+  // extension.

[Reilly Grant (use Gerrit), 2016/05/11 00:22:44]

Make this a separate sentence:

"It should also not be available to apps and extensions."

[juncai, 2016/05/11 00:32:36]

Done.

   if (base::CommandLine::ForCurrentProcess()->HasSwitch(
           switches::kEnableExperimentalWebPlatformFeatures) &&
-      base::FeatureList::IsEnabled(features::kWebUsb)) {
+      base::FeatureList::IsEnabled(features::kWebUsb)
+#if defined(ENABLE_EXTENSIONS)
+      &&
+      !render_frame_host->GetSiteInstance()->GetSiteURL().SchemeIs(
+          extensions::kExtensionScheme)
+#endif
+          ) {
     registry->AddService(
         base::Bind(&CreateUsbDeviceManager, render_frame_host));
     registry->AddService(