Track USB device interface claim state in Blink.

third_party/WebKit/Source/modules/webusb/USBConfiguration.h

Index: third_party/WebKit/Source/modules/webusb/USBConfiguration.h
diff --git a/third_party/WebKit/Source/modules/webusb/USBConfiguration.h b/third_party/WebKit/Source/modules/webusb/USBConfiguration.h
index e4676703faa0b448e910bdf5d625a513d381104f..72299b031bd5624ca45a72c9a998fd74dd48f725 100644
--- a/third_party/WebKit/Source/modules/webusb/USBConfiguration.h
+++ b/third_party/WebKit/Source/modules/webusb/USBConfiguration.h
@@ -26,6 +26,8 @@ public:
 
     USBConfiguration(const USBDevice*, size_t configurationIndex);
 
+    const USBDevice* device() const;
+    size_t index() const;

[juncai, 2016/03/17 01:21:11]

maybe use: configurationIndex() as function name? Similar to other functions
such as: configurationValue() and configurationName().

[Reilly Grant (use Gerrit), 2016/03/17 17:07:01]

The name configurationValue is verbose because the WebIDL matches the USB
specification's bConfigurationValue field for clarity. I'd rather write
configuration->index() than configuration->configurationIndex() if I have a
choice about it.

     const WebUSBDeviceInfo::Configuration& info() const;
 
     uint8_t configurationValue() const;