Make Progress support an arbitrary number of columns.

Make isolateserver_load_test use this, so the amount of data sent is used in the
middle column.

Make many Progress members protected.

Remove QueueWithProgress.set_progress() and fix the constructors so it is not
necessary anymore.

Review URL:

git-svn-id: svn:// 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed