Merge remote-tracking branch 'origin/master' into merge-to-aosp

Merged the following commits:
- e61717c Fix the virtual lock device
- f1fa93d Add fd event support to EventTaskRunner
- 5ca27be Removing trailing whitespace from speaker.cc
- b51b475 Adding handler for speaker device.
- fdf7515 examples: fix prerequisites for debian
- 82f215e Fixed check for pending tasks
- a627e12 Run CURL in background thread.