Don't set reason "Abnormal Closure"

Previously, WebSocketChannel arbitrarily used the reason text "Abnormal
Closure" when there was a failure leading to a 1006 close code. This is
not compliant with the WHATWG spec and doesn't match the old
implementation.

Changed to use no reason text.

BUG=340963
TEST=net_unittests --gtest_filter=WebSocket*, layout tests

Review URL: https://codereview.chromium.org/143693009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249350 0039d316-1c4b-4281-b951-d872f2087c98
Remove lower bound for ignoring generated background pages

BUG=

Review URL: https://codereview.chromium.org/156093002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@249351 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 249351