Do not set the network mode differently for LTE+CDMA

ro.telephony.default_network can be set if needed to set a different
value for LTE+CDMA. No need to hardcode preferred network mode in the source code.

Change-Id: Iae65f72a6a3bc31d500c5ecec87368a6f2a5d117
Fix deadlock of WebViewCoreThread

There was a deadlock in destroy process.
Investigation showed that WebViewCoreThread is waiting some
callbacks but in this case WebViewCoreThread can not resume
itself not to call notify method.

Flow:
1. CallbackProxy.sendMessageToUiThreadSync
2. WebViewClassic.destroy()
3. CallbackProxy.blockMessages()
4. CallbackProxy.handleMessage is called via MainThread
5. The WebViewCoreThread deadlock is occured.

The cases we have to call notify method are followings.
OVERRIDE_URL
CREATE_WINDOW
SAVE_PASSWORD
NOTIFY
OPEN_FILE_CHOOSER
JS_ALERT
JS_CONFIRM
JS_PROMPT
JS_UNLOAD
JS_TIMEOUT

Change-Id: I9d95ae500bf6338d77b32b5fa15de7cff5720d0f
Set foreground priority for shutdown receivers.

The broadcast of ACTION_SHUTDOWN has a timeout of 10 seconds. To
reduce the risk of hitting the timeout and speeding up the
shutdown sequence in ShutdownThread we set the priority of the
BroadcastReceivers to FLAG_RECEIVER_FOREGROUND.

We have seen that this change reduces the shutdown time when
the system is under heavy load.

Change-Id: I22cbf6af8cf6fc4bdefaa1c3da8a7eed7e7b7674