[ios] Adds code to support the iOS Handoff feature.

ios/chrome/browser/pref_names.cc

Index: ios/chrome/browser/pref_names.cc
diff --git a/ios/chrome/browser/pref_names.cc b/ios/chrome/browser/pref_names.cc
index 734e3b90e31d9bfc025a097290636c81311f2f9a..0f75891881a2994a01b2fc19aac88864a4f13d39 100644
--- a/ios/chrome/browser/pref_names.cc
+++ b/ios/chrome/browser/pref_names.cc
@@ -64,10 +64,6 @@ const char kIosBookmarkFolderDefault[] = "ios.bookmark.default_folder";
 // the bookmark promo dialog.
 const char kIosBookmarkPromoAlreadySeen[] = "ios.bookmark.promo_already_seen";
 
-// Whether Chrome should attempt to hand off the current URL to other Apple
-// devices that share an iCloud account.
-const char kIosHandoffToOtherDevices[] = "ios.handoff_to_other_devices";
-
 // Whether the user has enabled the Physical Web feature to surface URLs
 // broadcast by nearby devices.
 const char kIosPhysicalWebEnabled[] = "ios.physical_web_enabled";