wire up sampling profiler to dropbox

When system property "persist.sys.profiler_hz" > 0, SamplingProfilerService is
loaded to SystemServer. It creates a FileObserver, watching any new file in the snapshot
directory. When a snapshot is found, it is put in dropbox and deleted after that.

SamplingProfilerIntegration writes snapshots with headers. Headers are <name, value> pairs,
instantiated by caller.

Currently header format is (also in source comment):

Version: <version number of profiler>\n
Process: <process name>\n
Package: <package name, if exists>\n
Package-Version: <version number of the package, if exists>\n
Build: <fingerprint>\n
\n
<the actual snapshot content begins here...>

BUG=2732642

Change-Id: I2c1699f1728e603de13dbd38f9d8443cd3eecc06
5 files changed