Replace libusb in the Linux/Chrome OS USB I/O path.

device/usb/usb.gyp

Index: device/usb/usb.gyp
diff --git a/device/usb/usb.gyp b/device/usb/usb.gyp
index ef2cf899168808cbaec5b29e394e8ee5846d331b..bdac4ff94c9aceedd793f58f6957a02db6531142 100644
--- a/device/usb/usb.gyp
+++ b/device/usb/usb.gyp
@@ -103,6 +103,10 @@
           'dependencies!': [
             '../../third_party/libusb/libusb.gyp:libusb',
           ],
+          'sources': [
+            'usb_device_handle_usbfs.cc',
+            'usb_device_handle_usbfs.h',
+          ],
           # These sources are libusb-specific.
           'sources!': [
             'usb_context.cc',
@@ -122,6 +126,16 @@
             '../../chromeos/chromeos.gyp:chromeos',
           ],
         }],
+        ['OS=="linux"', {
+          'sources': [
+            'usb_device_handle_usbfs.cc',
+            'usb_device_handle_usbfs.h',
+          ],
+          'sources!': [
+            'usb_device_handle_impl.cc',
+            'usb_device_handle_impl.h',
+          ]
+        }]
       ]
     },
     {