Refactor ServiceDiscoveryDeviceLister class for general device discovery listing.
Make PrivetDeviceLister and  DnsSdDeviceLister use ServiceDiscoveryDeviceLister as a member object to do device listing.
Handle DeviceCacheFlushed events (i.e. network state changes)  in DnsSdDeviceLister for chrome.mdns

BUG=308354

Review URL: https://codereview.chromium.org/26800009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230085 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230085
drive: Show Local ID on chrome://drive-internals

Show Local IDs in "File System Contents" section.
Change column name in "Cache Contents" section from "Resource ID" to "Local ID"

BUG=None
TEST=Manually, look at chrome://drive-internals
R=kinaba@chromium.org, satorux@chromium.org

Review URL: https://codereview.chromium.org/32363010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230086 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230086