Cast: De-flake RTCP unittest.

RtcpTest.NtpAnd time had a bug causing it to fail 1 in 10 runs.

Review URL: https://codereview.chromium.org/64743008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236033 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236033
Incorporating logging into Cast: 
1. Adding logging to CastEnvironment.
2. Actually triggering logging within the cast library.
3. Adding thread checks.
4. Removing trace calls outside of the logging class.

Open issues: 
1.Use of rtp_timestamp and frame id is not consistent.
In addition, the AudioBus does not include these values.
2. There is a pending cl to switch frame_id to int. This cl does not include that.
3. There are a few more places to add logging.

As this cl is already big enough, all of the above will come in a follow-up cl.

Review URL: https://codereview.chromium.org/69603002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236034 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236034