Enable cast_unittests
And fixed associated errors

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=228002

Review URL: https://codereview.chromium.org/26486005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228515 0039d316-1c4b-4281-b951-d872f2087c98
Output trace clock markers on Android on start/end of tracing

The trace clock markers are for trace-viewer to synchronize the
clocks of the chromium trace and atrace when combining them.

BUG=294884

Review URL: https://codereview.chromium.org/26675003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@228517 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 228517