Change all DCHECK to CHECK to see if it can catch anything early.

Even with the help from two senior developers, I still cannot understand what causes the crashes. I am turning all DCHECK to CHECK to see if it can catch anything that is more helpful. Raman suggested not running this on dev channel. Also reduced the test probability for Canary in case this may cause more crashes (I tested this on my Linux box even with some erroneous server with packet drops or delays but did not notice any crashes yet).

NOTRY=true

BUG=273917

Review URL: https://chromiumcodereview.appspot.com/24278006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225188 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225188