Rename policy::EnterpriseInstallAttributes to chromeos::InstallAttributes.

Also replace some bare "new" with MakeUnique in BrowserPolicyConnectorChromeOS.

BUG=249513
TBR=achuith (chrome/browser/chromeos)
TBR=asargent (chrome/browser/extensions)
TBR=eroman (chrome/browser/net)
TBR=bauerb (chrome/browser/ui/webui)
TBR=hashimoto (chromeos/dbus)

Review-Url: https://codereview.chromium.org/2382833002
Cr-Commit-Position: refs/heads/master@{#422095}
47 files changed