Cast:Removing UMA

Review URL: https://codereview.chromium.org/150393005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250255 0039d316-1c4b-4281-b951-d872f2087c98
RawChannelPosix: Fix fatal-error-related behavior.
This change makes sure:
- For a raw channel, at most one READ error and one WRITE error notification will be issued. (And it is possible to get both.)
- After OnFatalError(READ), there won't be further OnReadMessage() notifications. But writes are not affected.
- After OnFatalError(WRITE), all WriteMessage() calls will fail. But reads are not affected.

TEST=RawChannelPosixTest.OnFatalError
BUG=None

Review URL: https://codereview.chromium.org/140653015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250256 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 250256