XmlUtils#readThisMapXml should handle null keys.

Both readThisValueXml & writeThisValueXml have been
implemented to handle values with "null" names.

Change readThisMapXml to allow such names as well, and
map them to the null key in the resulting HashMap.
readThisListXml and readThisSetXml already support
null names.

bug: https://code.google.com/p/android/issues/detail?id=63463

Change-Id: I1c93976656e45e7733113eb67d29b6bad5d25f1f
Fix memory leak in PatchCache

Patch object should be deleted when removing its corresponding
cache entry from PatchCache.

Change-Id: I8dfd7f557f6e5c6e9a9c04ba915372790e6f34f5
Signed-off-by: Sangkyu Lee <sk82.lee@lge.com>
Add explicit close of Scanner input

The UsbDeviceManager is using a Scanner to identify
the ALSA card/device numbers to use for USB Gadget
audio, with a FileInputStream as its input.

Since FileInputStream implements the Closeable interface
it provides a close() method that should be explictly
called in order to close the stream source and release
any system resources that it might hold.

Change-Id: Ia0ff86d1f3cdf8916becec9c8603915dcbf4d2c8