Get rid of DownloadItemImpl::UpdateProgress()

Changed SavePackage and unit tests to use DestinationUpdated(). This
function does the same work as UpdateProgress(). We stick to
DestinationUpdated() since it's part of DownloadDestinationObserver
interface (so already used elsewhere).

This patch makes the interface implementation as public to allow
access from SavePackage and unit tests. These functions were already
public in the interface itself.

TEST=content_unittests and making sure chrome is built

Review URL:

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