[Smart Lock] Add a setting to require close proximity in order for unlocking to work.

chrome/common/pref_names.cc

Index: chrome/common/pref_names.cc
diff --git a/chrome/common/pref_names.cc b/chrome/common/pref_names.cc
index 6ffe3324747ae82c4f55a72da2c9b6f50dbd5c60..bb05c0eec19637802f072a0d12a596799722cd05 100644
--- a/chrome/common/pref_names.cc
+++ b/chrome/common/pref_names.cc
@@ -1207,17 +1207,21 @@ const char kGCMChannelEnabled[] = "gcm.channel_enabled";
 const char kPushMessagingRegistrationCount[] =
     "gcm.push_messaging_registration_count";
 
+// Whether a user is allowed to use Easy Unlock.
+const char kEasyUnlockAllowed[] = "easy_unlock.allowed";
+
 // Whether Easy Unlock is enabled.
 const char kEasyUnlockEnabled[] = "easy_unlock.enabled";
 
-// Whether to show the Easy Unlock first run tutorial.
-const char kEasyUnlockShowTutorial[] = "easy_unlock.show_tutorial";
-
 // Preference storing Easy Unlock pairing data.
 const char kEasyUnlockPairing[] = "easy_unlock.pairing";
 
-// Whether a user is allowed to use Easy Unlock.
-const char kEasyUnlockAllowed[] = "easy_unlock.allowed";
+// Whether close proximity between the remote and the local device is required
+// in order to use Easy Unlock.
+const char kEasyUnlockProximityRequired[] = "easy_unlock.proximity_required";
+
+// Whether to show the Easy Unlock first run tutorial.
+const char kEasyUnlockShowTutorial[] = "easy_unlock.show_tutorial";
 
 // A cache of zero suggest results using JSON serialized into a string.
 const char kZeroSuggestCachedResults[] = "zerosuggest.cachedresults";