SnapdragonCamera: Synchronize shutter button click.

In monkey usecases, shutter button can be clicked really fast
even before app's state is set properly. This can lead to
multiple takepicture calls to lower layers. Since HAL
maintains state machine and doesnt allow such operations, error
will be thrown.

To avoid such situations, make onShutterButtonClick() a synchronized
method so that only one thread can access it at a time.

Change-Id: I19a2de7574452083d75204c84b89dac95d8b4f3e
1 file changed