Fix various operations in ChunkDemuxer that were not being applied to text tracks.

- Fixed range removal.
- Fixed shutdown on error.
- Fixed memory limit setting for testing.
- Cleaned up waiting for seek logic and documented behavior.

BUG=230708

Review URL: https://codereview.chromium.org/110693007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243756 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 243756