md-settings: Added settings for fingerprint unlock.

chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.cc

Index: chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.cc
diff --git a/chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.cc b/chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.cc
index 653539f33e80be9c0637cd9b0fab027a0bfffa81..75d915d8c77445a976ef3ab15bc8b577ca7d9975 100644
--- a/chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.cc
+++ b/chrome/browser/chromeos/login/quick_unlock/quick_unlock_utils.cc
@@ -36,6 +36,8 @@ void RegisterQuickUnlockProfilePrefs(PrefRegistrySimple* registry) {
   // 0 indicates no maximum length for the pin.
   registry->RegisterIntegerPref(prefs::kPinUnlockMaximumLength, 0);
   registry->RegisterBooleanPref(prefs::kPinUnlockWeakPinsAllowed, true);
+
+  registry->RegisterBooleanPref(prefs::kEnableQuickUnlockFingerprint, false);
 }
 
 bool IsPinUnlockEnabled(PrefService* pref_service) {
@@ -64,6 +66,14 @@ bool IsPinUnlockEnabled(PrefService* pref_service) {
   return base::FeatureList::IsEnabled(features::kQuickUnlockPin);
 }
 
+bool IsFingerprintUnlockEnabled() {
+  // Enable fingerprint unlock only if the switch is present. The fingerprint
+  // settings are under the lock screen so we cannot set it up without
+  // kQuickUnlockPin enabled, so make sure that feature is turned on as well.
+  return base::FeatureList::IsEnabled(features::kQuickUnlockPin) &&

[Dan Beam, 2016/12/13 19:53:23]

can we rename the Pin version to just kQuickUnlock?

[sammiequon, 2016/12/13 23:33:33]

Should I add a TODO and bug or do you prefer to do it in this CL?

[jdufault, 2016/12/14 17:58:57]

That seems confusing; in the context of kQuickUnlock, kQuickUnlockFingerprint,
kQuickUnlockPattern (likely future addition), kQuickUnlockPin is significantly
more descriptive than kQuickUnlock.

If the name is too long, I would prefer kPinUnlock, kFingerprintUnlock, etc.

[Dan Beam, 2016/12/14 22:25:17]

it's not too long, it's confusing that the PIN version enables the fingerprint
version of unlock

[jdufault, 2016/12/14 23:32:56]

Yes, I agree. I think renaming only the flag/pref makes sense since it accounts
for more than just PIN. Though I'm not sure doing so is worthwhile, as the flag
is going to go away soonish; it is on by default for m57.

[sammiequon, 2017/01/10 22:33:27]

I removed the dependence on kQuickUnlockPin.

+         base::FeatureList::IsEnabled(features::kQuickUnlockFingerprint);
+}
+
 void EnableQuickUnlockForTesting() {
   enable_for_testing_ = true;
 }