Revert 52334 - Http Cache: chain GetLoadState from transactions waiting for...

Revert 52334 - Http Cache: chain GetLoadState from transactions waiting for
access to an entry to the transaction that has exclusive
access to that entry.

This means that requests that are blocked on the single writer
lock of the http cache will report the load state of the
request that has the lock, and WAITING_FOR_CACHE is reserved
for requests that are actually waiting for the entry to be
created by the cache.

BUG=43582
TEST=net_unittests


Review URL: http://codereview.chromium.org/2976004

TBR=rvargas@google.com

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=52405