Add error description to the DidFailProvisionalLoad callback.

This will add an error description field to the TabContentsObserver::
DidFailProvisionalLoad callback.
The change should not have any impact on current behavior.

This is needed for the Chromium port on Android.

BUG=none
TEST=base_unittests,content_unittests,browser_tests


Review URL: http://codereview.chromium.org/8142032

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@104895 0039d316-1c4b-4281-b951-d872f2087c98
19 files changed