Implement basic USB device enumeration on Android.

content/app/android/library_loader_hooks.cc

Index: content/app/android/library_loader_hooks.cc
diff --git a/content/app/android/library_loader_hooks.cc b/content/app/android/library_loader_hooks.cc
index 487d9738a61d431b02e9ac49ccf5fbaf5c74173b..21e51b36b924d0770a548e75f3e9d2177d279e97 100644
--- a/content/app/android/library_loader_hooks.cc
+++ b/content/app/android/library_loader_hooks.cc
@@ -26,6 +26,7 @@
 #include "content/public/common/content_switches.h"
 #include "content/public/common/result_codes.h"
 #include "device/bluetooth/android/bluetooth_jni_registrar.h"
+#include "device/usb/android/usb_jni_registrar.h"
 #include "media/base/android/media_jni_registrar.h"
 #include "media/midi/midi_jni_registrar.h"
 #include "net/android/net_jni_registrar.h"
@@ -75,6 +76,9 @@ bool EnsureJniRegistered(JNIEnv* env) {
     if (!device::android::RegisterBluetoothJni(env))
       return false;
 
+    if (!device::android::RegisterUsbJni(env))
+      return false;
+
     if (!media::RegisterJni(env))
       return false;